- 5/25/2025
In Peru, Quechua villagers revive the astonishing engineering lore of their Inca ancestors as they weave a traditional bridge from grass fiber and suspend it across a gorge. Meanwhile, an architect and an amateur archaeologist try to settle their long-standing arguments about the secrets of Inca stone walls. How did the ancient masons fit giant, irregular blocks together so perfectly that a knife blade cannot be pushed between the joints? As they join our experts in puzzling over Inca mysteries, NOVA viewers will glimpse the splendors of Machu Picchu and masterpieces of ancient Peruvian weaving and gold work.
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TVTranscript
00:00The Peruvian Andes of South America are among the most rugged mountain chains on Earth.
00:14Battered by earthquakes, volcanoes, and powerful storms, the Andes are a dynamic land of environmental
00:21extremes.
00:25Any Amazon jungle quickly gives way to jagged, 20,000-foot-high peaks.
00:34The spine of the Andes separates arid coastal desert from bleak, high-altitude plateau.
00:42Too dry or too vertical for normal living, this land seems an unlikely place to find
00:48a great civilization.
00:51But 500 years ago, an ambitious Andean people called the Inca were building spectacular
01:00cities in the clouds.
01:09Their intrepid engineers linked these mountaintop citadels with a phenomenal system of roads
01:17and gossamer-like suspension bridges made only of grass.
01:27Five-hundred years ago, before the Spanish came to the New World, the Inca Empire was
01:31the greatest in the Americas, stretching almost the entire length of the Andes.
01:37The Incas were certainly the strangest and most bizarre civilization that the Earth has
01:44ever seen.
01:45They had none of the things that we think of as the prerequisites for a major civilization.
01:49No arch, no wheel, no codified mathematics.
01:53They couldn't write.
01:54They couldn't even scratch down an arithmetic problem.
01:56And yet they could do this amazing engineering.
02:00The Inca's engineering medium was stone.
02:04In their walls and buildings, they showed a mastery over stone that is unrivaled.
02:10Made of mortar, the Incas created walls of interlocking blocks that have successfully
02:16withstood earthquakes for centuries.
02:24But their interest in stone went beyond the utilitarian.
02:28The Incas worshipped rocks.
02:33They carved intricate designs on natural outcrops and poured Chichime's beer or sacrificial
02:39blood down the channels to honor their mummified ancestors housed in rock-cut chambers below.
02:59Choosing high vantage points at sacred sites, the Incas created mysterious stone columns
03:06dubbed hitching posts of the sun.
03:10They worshipped the sun and may have used the shafts for sighting stars.
03:19Blending their stonework into the natural landscape, the Incas carved rocks to mimic
03:25the shape of the mountains behind.
03:31But their most impressive and mysterious stonework is found in the walls of their citadels.
03:38Giant blocks, some weighing a hundred tons, sit next to each other so precisely that not
03:45even a razor blade can fit between them.
03:50Without iron tools, draft animals or the wheel, how did the Inca builders move and set such
03:57large blocks?
04:01To answer this question, Nova invited several experts with widely different backgrounds
04:07to come to Peru.
04:14Professor of architecture Jean-Pierre Protzen studies the Inca's use of stone.
04:24He's written a book about Inca architecture and has some definite ideas about their construction
04:29methods.
04:38Ed Frankobont is both an anthropologist and a building contractor who lived in a Peruvian
04:44village for several years.
04:46His particular interest is how the Inca builders organized their labor force.
04:59Felipe Petit is the man who walked a tightrope between the towers of the World Trade Center.
05:12He wants to know how the Inca builders used grass to make the strong ropes that support
05:16their high suspension bridges, and he's come here to help build one.
05:28Vince Lee is an architect and explorer who has traveled extensively in the Andes looking
05:33for lost Inca sites.
05:36He has a theory about how the Inca stonemasons made such precise joints with such giant stones.
05:47A good place to start looking for clues is the citadel overlooking the town of Ollantaytambo.
05:59About 500 years ago, a sun temple was under construction inside the fortress.
06:06So with all these blocks of stones here, this is clearly a construction site that was
06:10abandoned in progress.
06:11The question is, where did these stones come from and how did they get here?
06:17Well they came from the quarries on the other side of the river at the base of this mountain
06:23here.
06:27The team decides to follow the route to the quarry taken by the ancient stone haulers.
06:41The hike will take them down a sloping ramp to the valley floor.
06:46Along the way, they find massive blocks abandoned by the Inca workers.
06:55The villagers call these rocks piedras cansadas, weary stones.
07:03One legend tells of stones that grew tired, wept blood, and refused to move.
07:09And so is there.
07:12So this is where the quarry is.
07:17The lower quarry at the bottom of this rockfall, you can see some ramps.
07:22The other quarry is way up there at the foot of the cliff.
07:27Jean-Pierre, JP to his friends, leads the team along the remains of a roadway that leads
07:33to the quarry.
07:39Actually a rockfall created by rocks eroding from the cliffs above.
07:45Here they find a 70 ton stone that Inca quarry workers had turned into a rectangular block.
07:53JP believes that all the boulders were first squared off in the quarry.
07:59But how did the Incas transport these heavy blocks down the mountain and up to the Sun
08:04Temple on the other side of the valley?
08:09Spanish chronicles tell us that the Incas did not possess the wheel or strong draft
08:14animals like oxen.
08:18David Canal, a community leader and Inca descendant, believes they hauled the blocks by hand.
08:28He's organized a team of pullers to transport a one ton rock along the same route taken
08:34by the Incas between the quarry and the citadel.
08:39For most of its length, the ramp has a gentle slope, but halfway down the mountain the incline
08:45suddenly turns into an almost vertical 800 foot chute to the valley below.
08:57With a block more than 10 times the size of this one, it must have been extremely difficult
09:02for the ancient stone haulers to negotiate this chute.
09:09Unlike the Inca blocks observed on the transport route, this boulder has not been squared off
09:15and it tumbles out of control.
09:19Probably not the way the Incas wanted to see it now.
09:21No, no.
09:22Absolutely not.
09:23And you know, if it turned this way it was kind of cylindrical, it was kind of easy for
09:26it to get rolling where a big square block might not have done that.
09:32Having gotten the boulder down in pieces by a distinctly non-Inca method, everyone
09:37hopes to do better with the next challenge, getting a block across the Urubamba River.
09:47At this time of year, the water level is at its lowest and the river looks quite placid.
09:52But after the rainy season it becomes a torrent, impossible to ford.
10:06David believes the Inca hauling teams would have chosen to cross at the shallower stretch.
10:23But even here there's a stiff current and many of his men can't swim.
10:31To appease the spirits of the river, David has arranged for an offering of cane alcohol.
10:45The wet stones are slippery for the men, but this turns out to be an advantage when it
10:50comes time to pull the rock.
11:20The task of getting the rock across the Urubamba turned out to be much easier than everyone
11:49had imagined.
11:53But crossing the fields on the valley bottom is much more of a problem because the stone
12:01acts like a plow digging into the soft ground.
12:09There was probably once a road crossing the valley, but it has been destroyed by centuries
12:14of farming.
12:16Information has been obtained to excavate one of the blocks abandoned in Inca times
12:21to see if there is any evidence of a roadbed underneath.
12:25What turned up underneath was a layer of small stones on top of what appears to be a prepared
12:30gravel road base.
12:32So the resulting surface that the stone appears to have actually been bearing on is just these
12:38stones about the size of a softball, not necessarily round, but you know, and that's not unlike
12:43the surface we find on the ramps today still.
12:46Now that they have found the kind of road used by the Inca stone haulers, the team wants
12:51to see how difficult it would be to drag a much heavier block on a similar surface.
13:03In the plaza below the citadel, they find a genuine 15-ton Inca block, and the sloping
13:09cobbled surface is a good approximation of the 8-degree ramp that leads up to the Sun
13:14Temple.
13:15To pull the block, David has assembled a team of 250 men, women, and children from Ollantaytambo
13:28and neighboring villages.
13:34There's a festive atmosphere.
13:36The men's turned out to see the great block being dragged through town.
13:49Unfortunately, the stone refuses to budge.
13:59But after another offering of cane alcohol and some levering, the stone finally comes
14:04unstuck.
14:24The ease with which the block travels on the cobbled surface proves that it could have
14:29been dragged up the slope to the Sun Temple.
14:37I had no doubt that we could do it.
14:39Our ancestors did it, so I knew we could do it too.
14:43Human labor can accomplish anything.
14:52The determination displayed by David's people makes the speed and scale of the Inca's empire
14:58building achievements much more understandable.
15:05According to legend, around 1450 AD, a leader called Pachacuti, whose name means Earthshaker,
15:13began an aggressive military campaign that transformed the Incas from a small Cusco Valley
15:19community into a juggernaut that swallowed up all its Andean neighbors.
15:26In return for the benefits of a stable state, conquered peoples paid tax to their Inca masters
15:34in the form of labor.
15:41This huge workforce enabled Pachacuti and his successors to build the infrastructure
15:46that could support their rapidly expanding territorial gains.
16:03In the Urubamba Valley, wide, rambling sections of the river were placed in canals to create
16:10cultivatable land.
16:15Forests watered by elaborate irrigation schemes climbed the mountainsides, further increasing
16:21food production.
16:23On the peaks above the Urubamba River, the Inca lords built a chain of remarkable citadels
16:31in the sky.
16:33The most magnificent and mysterious of all, Machu Picchu.
16:42It's difficult for us to grasp the scale of the Inca's imagination and ambition in
16:48producing places like this.
16:51As archaeologists, we like to work with potsherds or tools or walls or a building, things that
16:57are people scale.
17:00But the Inca's vision was much bigger than that.
17:09The real Inca media was the entire immense Andean landscape around him.
17:17He spent extra time to find very special places within the Andean landscape, spent time studying
17:25them to understand their true nature, embellished them with stone, ran sparkling and rushing
17:34water through prepared water courses, and in the end produced works of singular beauty
17:42that represent a harmony with nature that few other civilizations have achieved.
17:54So remote was its location, Machu Picchu's existence remained a secret from the time
18:00of the Incas until the early part of this century.
18:12But 30 miles upriver, the town of Ollantaytambo has been lived in continuously since the time
18:18of the Inca.
18:23Its buildings are well preserved.
18:28But the very finest Inca stonework is found in the citadel above the residential quarters.
18:38Replicating joints like this is the challenge J.P.
18:41Protzen and Vince Lee have set themselves.
18:46You know, J.P., this part of Ollantaytambo has always been one of my favorites.
18:49I mean, this is Inca stone masonry as good as it gets.
18:52Don't you agree?
18:53I bet.
18:54It's not just the craftsmanship, it's just the playfulness of the joining and the problem
19:00that they elected to solve is just so complicated.
19:02It's wonderful.
19:03I mean, you really see that here they perfected their skills.
19:06Yeah.
19:07And you know, the other thing, it seems to me that where other cultures use stone as
19:12a material for sculptural decor of one kind or another, these guys just use the stone
19:18itself.
19:19They're just telling you that stone is itself a beautiful material.
19:22Don't have to carve anything into it, really.
19:24No, this is sculpture.
19:25Yeah, exactly that.
19:26Yeah.
19:27You know, people often say, oh, you can't get a knife blade in the joints of Inca.
19:31You can't get anything in this.
19:32Not even an eraser blade.
19:33No.
19:34No, it's an absolutely perfect joint.
19:35Yeah.
19:36I mean, the craftsmanship is mind-boggling, especially if you try to do it, if you try
19:42to duplicate it yourself.
19:44J.P. has duplicated Inca stonework using Inca tools.
19:50In an ancient quarry, he discovered some rounded stones that probably came from the river.
19:57Using these as hammer stones, he found them as effective as the modern steel chisels used
20:02by stonemasons today.
20:13To create a beveled edge, J.P. used a smaller hammer stone.
20:21The resulting tool marks are identical to those found on Inca masonry, rough in the
20:26center and smooth at the edges.
20:30But how did the Inca masons go about setting the stones?
20:36A half-finished citadel wall provides an important clue.
20:43To achieve the perfect Inca joint, an imprint is marked on the block below.
20:49The area that will seat the new block is then hammered out.
21:03Repeated fittings fine-tune the joint.
21:08Spots where stone dust is compressed indicate raised areas that need more hammering.
21:19Using ever-smaller hammer stones to avoid damaging the edges, J.P. finished the joint
21:25within a few hours.
21:28It shows that with the sort of simple tools that I have found in this quarry, it is absolutely
21:34possible to achieve the kind of perfection of stonework that we observe throughout Cusco
21:40and the Inca Empire.
21:43J.P.'s method works well with small stones that can be easily maneuvered.
21:50But as the stones get bigger, handling them becomes increasingly difficult.
21:59Here, at the Inca fortress of Saqsayhuaman, the trial-and-error method of setting giant
22:05multiple-storied blocks of stone together is the only way to achieve the perfect Inca
22:11joint.
22:13Here, at the Inca fortress of Saqsayhuaman, the trial-and-error method of setting giant
22:19multi-ton blocks seems a daunting prospect.
22:25But despite their size, the blocks in the retaining wall all have the famous Inca fit,
22:31mortarless and snug.
22:34The answer may be a simple builder's tool called a scribe, a tool that may have enabled
22:40the Inca masons to make joints without any painstaking trial-and-error.
22:51Back in Ollantaytambo, Vince is about to use his scribe as he attempts to make a perfect
22:57Ollantaytambo, Vince is about to use his scribe as he attempts to make a perfect Inca
23:02joint between two stones his masons have worked on for several days.
23:11We're getting the rock into position to scribe this prepared joint into this one that's
23:17yet to be prepared.
23:19And so far, everything we've done, anyone fitting these two rocks together would have
23:23to do.
23:24You would have to rough cut your rocks and basically decide which rock was going where,
23:28and you'd have to get them in position.
23:31Now is the point where the method I'm proposing perhaps differs from others because what I'm
23:36saying is that by using this scribe, this end, this blunt end is designed to work against
23:42a previously prepared smooth surface.
23:45Now what we have to do is make this edge exactly match it.
23:49And the way we do that is by taking this scribe and running it down this pre-finished
23:54surface, maintaining the string hanging through the center of its hole with this little plumb
24:00bob so that we don't accidentally mess up our joint by allowing the scribe to move in
24:05this plane.
24:06As long as we keep the string in the center of the hole and as long as this is rubbing
24:12against that pre-finished surface, all we have to do is chop this rock out so that this
24:17end of the scribe exactly fits no matter where we put the scribe.
24:23Then we can achieve the fit we want by moving this rock one more time, simply closing the
24:28joint.
24:29End of story.
24:33Time constraints have forced Vince's men to use steel chisels to work the hard andesite
24:40rock.
24:59Well, this is it, the moment of truth for Vince's project.
25:02He's been scribing and chomping and chipping and polishing.
25:05And right now these two stones are supposed to go together like inclamation.
25:09Be right close together.
25:11What do you think?
25:12Will it work?
25:13Will it happen?
25:14It's absolutely right.
25:15It's time to stop talking and start moving rocks.
25:16So let's do it.
25:36Yeah.
25:37The joint that we've gotten is certainly not as good as the ones we've seen up in the ruins.
25:41But it isn't bad.
25:42What we did here today is we fitted two large rocks together, moving them together only
25:47one time.
25:48That's the essence of my idea, basically.
25:51We didn't have to try this back and forth at all.
25:55We fit it once and we got a pretty good joint.
25:57If you set us down here for three more weeks, we'd do twice as good a job, I believe, because
26:02we know now all the mistakes that we made and we know not to make the next time.
26:06But I think it's not too bad.
26:08The second stage of Vince's experiment is much more complicated.
26:12He has to create a corner joint that fits perfectly with neighboring stones, both horizontally
26:18and vertically.
26:19In order to fit this corner right here of this stone into this seat that Hector is shaping,
26:27we have to bring this stone around and prop it up above the seat that it's intended to fill
26:33and then put poles under it.
26:36And you'll see perhaps these huecos or these notches in the rock.
26:40And that's what they're for.
26:42We'll put poles under the stone.
26:44We'll probably leave some stones at this end, under the very tail end of the rock.
26:48And we'll be able to remove all these stones so that it's hollow underneath the stone.
26:52And that gives us a place to use the scribe.
26:56And the scribe in this case is just like the other one, but it will be used in a 45-degree orientation.
27:02It'll come down the rising face and across the base.
27:05And you see in order to get all the way across, we have to move all these stones out of the way
27:09underneath the rock.
27:11That's undoubtedly the most tricky part of this technique.
27:15Yeah.
27:18Well, yeah, I was one of the people who was healthily skeptical of this whole system.
27:22But, you know, it looks dangerous, it looks hard.
27:24And with a bigger stone, I think it'd be more dangerous and more hard.
27:27I still have my doubts, but there is an outline of a method.
27:30That stone is standing there, actually, in the air above the space it's supposed to go in,
27:35propped up on those pieces of wood.
27:39Vince believes that notches cut into the giant blocks at Saqsaywaman support his theory.
27:47But if it's a precarious operation propping up a half-ton rock,
27:51what would it be like with a 25-ton boulder?
27:59Looks very much like the surface we already have is very close to what we want.
28:05As we move it up, it comes out to three-eighths.
28:09So, just offhand, it looks like maybe we have to take a little more material off here.
28:21We're now going to drop the stone into its seat and see how well we did.
28:27With Vince rapidly losing his voice, his team is about to begin the final test.
28:33With his voice, his team is about to start the most hazardous part of the operation,
28:39lowering the block into place.
28:42By tipping the stone a little bit at a time, pull out a stick here, a stick there,
28:46until the whole thing creeps into place.
28:48This seems to me inherently less stable, and I think with a huge stone,
28:54it would be even more unstable.
29:04It's clear that Vince and company need to refine the procedure
29:08for getting the block off the stilts and into position,
29:12particularly if this method is to work with stones weighing many tons.
29:33Yeah, yeah, I know that.
29:37This isn't bad.
29:39Well, we've seen that this can be done, but the question is, is this how it was done?
29:43Did the Incas actually use this scribing method to construct their stone walls,
29:47to find their fine joints? I don't know. Do you think so?
29:49Well, as I said at the outset, I'm not sure we'll ever know how the Incas did it.
29:53The point of this was to try to find a way that worked, and that would work with big stones.
29:57Now, in the case of the little joint we just fit here,
30:00we spent 12 days doing the rough work that any technique would involve,
30:04and one day doing the scribing.
30:06That tells me that the scribing is an efficient way to make the joint.
30:09Had we moved the rock five times and so forth,
30:12we might have spent 12 days doing the rough work and three days making the joint,
30:16a less efficient way to do it.
30:18But which way the Incas would have used, I don't know that we'll ever know.
30:30The annual Ollantaytambo bullfight is in full swing,
30:34and yet another demonstration of how the Incas might have created their amazing stonework
30:39is being set up for a rather skeptical audience.
30:43How curved it is affects where it's focusing.
30:47That's what you see.
30:49Professor Ivan Watkins teaches geoscience at St. Cloud University in Minnesota.
30:56Ivan and his wife Bertha are here to test his theory
31:00that the Incas used gold parabolic mirrors
31:04to concentrate sunlight into a high-temperature beam that could melt stone,
31:09or as Ivan would say, thermally disaggregated.
31:14You see that little image of the sun there?
31:16Yeah.
31:17That's the sun.
31:20Okay, now, the idea of this whole thing is to have an image of the sun
31:25from the big mirror projected across to a plain mirror
31:30and then use another parabolic mirror to direct the light
31:35to whatever is going to be thermally disaggregated.
31:40In this case, what we would thermally disaggregate would be a rock.
31:44Okay, now, you can see the bright spot that is there.
31:48If Ivan's parabolic mirrors work,
31:51they'll concentrate the sun's energy 10,000 times
31:55and melt this small piece of rock.
31:58Why don't I knock that little piece of rock off for it?
32:01Several years ago, Ivan was touring Inca sites,
32:05and this half-finished stone,
32:07was the first to be discovered by scientists.
32:11He was touring Inca sites,
32:13and this half-finished stone at Machu Picchu attracted his attention.
32:18Certain marks on the rock struck him
32:21as a clear indication of the use of parabolic mirrors.
32:26Archaeologist Helene Silverman is not convinced.
32:30Think that's possible?
32:31I think it's ridiculous.
32:33There's absolutely no evidence that the Incas were using mirrors.
32:37And what's more, it's very clear what the technology of this is.
32:40They were chipping away at this.
32:42I agree 100% with you that this is a classic surface
32:46that's made by pecking the stone.
32:48Every one of these rocks has peck marks all over it.
32:51But could stone hammers peck out the inside right-angled joints
32:56that are so common in Inca walls?
32:59Ivan was convinced they couldn't.
33:03With no evidence of metal tools,
33:06Ivan reasoned the only alternative was a ray of amplified sunlight.
33:12Unfortunately, Ivan's prototype mirrors are not truly parabolic
33:16and failed to concentrate the sunlight effectively.
33:20I'm not getting the temperature high enough there to pop him off.
33:26The crux of Ivan's argument is that solar power
33:30concentrated through parabolic mirrors
33:32is the only way the Inca stone cutting
33:34that we've seen here at Ollantaytambo could have been done.
33:37But how about the stones that we've seen that have clear hammer marks on it?
33:41I mean, are you saying those were not?
33:43I'm not at all sure when you say they have clear hammer marks.
33:46What is the difference between taking...
33:49I think I want out of this. This picture is ridiculous.
33:53This is really ridiculous.
33:57I need some goggles, though, because I just got blasted.
34:02I want to see this guy cut a stone like I can do, and then I talk.
34:07But otherwise, that makes no damn sense.
34:10If you can find a radius of curvature again...
34:13This is ridiculous.
34:15...then it is necessary that, indeed,
34:18that was not produced by hammering with a stone.
34:20All corners, inside corners in Inca masonry are rounded.
34:26There are no sharp inside corners.
34:30And J.P. appears to be right.
34:33There are no sharp right-angled joints to be found.
34:38And even the tightest could have been created
34:41by polishing with a small hammer stone.
34:48Let's try burning this popsicle stick.
34:51Watch my finger. I've only got ten.
34:53Okay, I'll try to not de-digitate you.
35:00It doesn't seem to be Ivan's day.
35:03Just singeing a popsicle stick is a problem for his mirrors.
35:19Here we go. There's flame. There's some flame.
35:29Down at the arena, things are not going much better
35:32for part-time matador Philippe Petit,
35:35where even the bulls refuse to get fired up.
35:39Bravo!
35:58At its height, the Inca's rugged domain
36:01extended for almost the entire 3,500-mile length of the Andes.
36:08To control their diverse empire from the capital, Cusco,
36:12the Inca's built a 14,000-mile network of all-weather roads.
36:24The vertigo-inducing terrain forced Inca engineers
36:28to build on steep mountainsides,
36:31sometimes carving trails right out of the living rock.
36:36Downhill, then uphill.
36:38This is really the nicest part of the trail.
36:40I know. These steps in the living rock are just fantastic.
36:43Helene Silverman has joined Ed Frankemont
36:46to explore one of the most dramatic sections of the trail.
36:53Not possessing the wheel,
36:55the Inca engineers designed the trails
36:58for foot traffic and cargo-bearing llamas.
37:01Inca relay runners stationed every few miles
37:04carried messages at a speed of 150 miles a day.
37:16The system, the road system, was so good
37:19that in ten days a message could be transmitted
37:23from Quito in Ecuador to Cusco, the Inca capital.
37:27That's about as fast as modern-day postal service
37:31can send a letter between these two capital cities today.
37:40A number of great rivers posed the most serious obstacle
37:44to the Inca road builders,
37:46particularly after the rainy season,
37:49when these waterways became raging torrents,
37:52impossible to ford on foot or cross by ferry.
37:56The ingenious solution to the problem?
37:59Suspension bridges that could span up to 150 feet.
38:06One of these bridges crossed the gorge above the Aparimac River,
38:11near the remote village of Huinchiri.
38:15The people here still build grass suspension bridges
38:19as their ancestors did 500 years ago.
38:22It's said these bridges can be built in just three days.
38:28Ed and Helene want to see how the community organizes itself
38:33into such an effective labor force.
38:42But one day before construction is due to start,
38:45the only sign of life near the bridge site
38:48is the harvesting of grass by Clotilda Vilcas and her family.
38:58It's sobering to realize that these dry-looking stalks
39:02will bear the weight of people
39:04crossing 60 feet above the Aparimac River.
39:07Clotilda's contribution to the community effort
39:10is to twist the grass into 50 yards of two-ply rope
39:14and deliver it tomorrow morning.
39:18Clotilda's contribution to the community effort
39:21is to twist the grass into 50 yards of two-ply rope
39:25and deliver it tomorrow morning.
39:48As the first day of construction begins,
39:51the usually barren hills are suddenly crowded
39:54as local people start arriving at the bridge site.
40:00Villagers responsible for producing rope
40:03deliver their 50-yard quota.
40:09In total, the bridge will require over 7,000 yards
40:13In total, the bridge will require over 7,000 yards
40:17of half-inch-thick Koya grass rope.
40:24Before construction begins,
40:26spiritual matters must be attended to.
40:29Chief bridge builder Victoriano Arisapanam
40:32is making an offering to Pachamama, Mother Earth,
40:36to ensure her blessing on the enterprise.
40:40This ritual requires the consumption
40:43of large amounts of alcohol by the village leaders.
40:50These people are every bit a part of the engineering
40:53as the bridge folks are.
40:55What they're doing is making the bridge strong and safe and last,
40:59and their job is to sit here and construct the payments
41:02that we make to the earth and make sure
41:05these cables go across and are completely strong.
41:13High wire walker Philippe Petit cannot resist
41:16entertaining the crowd.
41:18With his lifelong passion for knots, rigging and cables,
41:21he's thrilled to be part of the effort.
41:25Take it.
41:32Attendance at the bridge site is carefully noted.
41:35By midday, almost 500 people have turned up.
41:44The rope is divided up into sections,
41:47each containing 24 strands, 150 feet long.
41:55¿Cómo es? ¿Cómo es?
42:06The ropes are twisted together tightly and evenly.
42:12The flimsy-looking strands that were delivered in the morning
42:15are suddenly transformed into something substantial enough
42:19to entrust one's life to.
42:25¡Cala! ¡Cala! ¡Cala medio! ¡Cala medio!
42:33They are stranding the three main ropes into the final rope,
42:36into one of the final rope.
42:38So they have to keep the regularity of the braiding,
42:41and they have also to be very careful about the torsion.
42:44Sometimes they yell, noodle, the knot,
42:46because something is twisted not too much,
42:48so it creates a... it creates, you see?
42:51When you take a rope like this, and you go like that,
42:54you see it creates knots, you see?
42:56So you have to take it out.
43:02Oh, it's beautiful, because each family did one little piece,
43:05each community brought their own rope.
43:07Those ropes which are like your little finger
43:10are braided into a bigger one, and then into those big ones,
43:13and now three of those big ones, it's really communion.
43:21By the end of the first day,
43:23these load-carrying cables are delivered to the bridge site.
43:30Each cable weighs about 200 pounds.
43:35It's hard, heavy labor, but enthusiasm never wanes.
43:40Bridge building is as much a party as it is work,
43:43and probably always has been.
43:52The bridge builders are farmers living in homesteads
43:56scattered all over the high Puna grassland.
43:59They are well adapted to working at altitudes of 14,000 feet and more,
44:04having long ago developed large-capacity lungs
44:08and short, strong legs for climbing steep mountainsides.
44:13Like her ancestors in Inca times,
44:16Clotilda is very self-sufficient.
44:19She makes clothes for the family
44:21and barters for the food that she doesn't grow herself.
44:30Today, Ed has asked her to prepare a special Inca dish,
44:35guinea pigs.
44:37I think I have problems because we keep them as pets in the United States.
44:41Well, it's not a dog.
44:42I know.
44:43No, and I know the whole history of guinea pigs.
44:45There you go.
44:46I know they're very important, domesticated.
44:48That's right, these are what you've been judging me not for.
44:50I know, I've got caches of them.
44:54They're succulent.
44:55Mm-hmm.
44:57They're very nutritious.
44:58They're very nutritious.
44:59They're very nutritious.
45:00They're very nutritious.
45:01They're very nutritious.
45:02They're very nutritious.
45:03They're very nutritious.
45:04They're very nutritious.
45:06Don't you like the huacatay?
45:11Potatoes also came from the land of the Incas,
45:14but they've caught on better in the rest of the world than guinea pigs.
45:19They eat well because the hard work on the bridge is about to begin.
45:30The next morning starts with tossing a rope across the river.
45:35This will be used to pull the main cables over the gorge.
45:44Nova has asked that the bridge cables be strong enough
45:47to carry at least five people and two llamas,
45:50the kind of load it might have supported in Inca times.
45:57On either side of the chasm,
45:59there are stone abutments that were constructed by the Incas.
46:04They were built into the side of the mountain
46:06in order to support the weight of the bridge.
46:13The cables are wound around stone beams
46:15anchored into the floor of the abutments,
46:18and they will eventually be securely tied off.
46:28But first, the cables must be tightened inch by inch
46:32to get rid of any slack.
46:38Pulling the six cables taut takes the rest of day two.
46:45If all goes well, the bridge will be ready to cross in 24 hours.
47:03The morning of the third and final day
47:06finds the riggers swinging in the wind
47:0960 feet above the ApurÃmac River.
47:14It is not a vision that inspires confidence,
47:17but Helene puts on a brave face.
47:20I feel a lot better about crossing this bridge now
47:23than I did before I saw it being built,
47:26and I think that it's structurally sound,
47:29I can even see that as the people are building the bridge
47:33they're already walking out over it before it's even finished.
47:49Philippe, who has never felt more in his element,
47:52has been helping the riggers all morning.
47:56OK, well, this bridge, I should say this piece of art,
47:59is now near completion.
48:03They are tying the foot ropes together,
48:06and they are doing the connection between the handrail and the foot.
48:11And it's done very fast.
48:56Pablo Javier, Patricio Huyca,
49:00Paulina Aima, Martina Aima,
49:05Justina Huyca...
49:07With the bridge complete, a roll call is taken
49:10to confirm who gets paid.
49:14The Incas were great record keepers, too.
49:17It's been said that if even a pair of sandals
49:20were missing from their inventory, they would know.
49:24But how did they handle such information
49:27without writing or arithmetic?
49:29Well, the Incas never had a written system,
49:31but it wasn't anywhere near as much of a disadvantage
49:34as you might think, because they were able to store
49:37really abstract and complicated information
49:39using textiles as a medium.
49:41Right here, what I'm making is a small Inca textile,
49:44a kipu, a series of knots,
49:46which keeps records on events that happened.
49:48In this case, I'm talking about how many people it took
49:51to build the bridge, how much it cost,
49:53the records we might keep.
49:54This is a read-only document.
49:56After it's all done, what I'm going to be able to do
49:59is put on the finished records of what's going on here.
50:02It's not a counting device like an abacus
50:04that counts as you go.
50:06Here, I've recorded how many people there were
50:09from the community of Winchiri who showed up to work
50:12for those six days.
50:14And here is how much we paid all their workers,
50:16and over here is how much we paid the authorities
50:19who did the bridge for us.
50:21We want to get back records years from now
50:23on how this bridge was made, how long it took,
50:25how many people it took, and what it cost.
50:27We'll be able to code them and keep them forever
50:30in a knot of string like this.
50:32Now the workers are taking a rest,
50:34and I am alone on that bridge, and I feel like a kid
50:37who is being given a giant gift,
50:39and I start enjoying myself as a wire worker
50:42as I can feel the balance a bit.
50:45You see here?
50:47So I don't know if I can even walk like this, but...
50:55With an Inka bridge, all the load is carried
50:58by the four cables which make up the footpath.
51:01The handropes are only for balance.
51:07Helene is warned that leaning on them too heavily
51:10could cause the bridge to flip over.
51:13I want to look down, but I'm afraid to look down,
51:16because I'm looking at everybody across.
51:19I know I can do this.
51:21I think I'm going to be sick.
51:24No, I'm not.
51:28The llamas are even more reluctant
51:30to cross the bridge than Helene.
51:38Well, this bridge is certainly tremendous.
51:40It's an amazing example of how the Inkas were able
51:43to accomplish tremendous amounts of work
51:45in a short period of time, billowing all over the Andes.
51:51In terms of labor organization,
51:53I feel as though I've been transported back 500 years
51:56to the Inka times.
51:58I can just imagine the Native leaders doing the census,
52:01saying, okay, guys, ladies, you make the rope.
52:04Men, you lay out the strands.
52:06We are going to build the bridge.
52:08This is your labor tax.
52:13The Inkas were the largest empire
52:15of the pre-industrial world, and certainly the richest.
52:18They had a control over this land,
52:21this wonderful and severe land of the Andes
52:24that nobody could ever imagine.
52:26How they accomplished all these things,
52:28we're just beginning to ask the right questions.
52:44Now, log on to another lost empire, ancient Egypt.
52:49At NOVA's website, navigate the tunnels, tombs,
52:52and temples of the pharaohs,
52:54and follow a real-time excavation at Giza.
52:57Experience pyramids, the inside story,
53:00on NOVA PBS online adventure.
53:14¶¶
53:27To order NOVA's Secrets of Lost Empires
53:30miniseries on videocassette,
53:32call 1-800-255-9424.
53:35This 5-hour set is $69.95, plus shipping and handling.
53:40Individual programs are also available for $19.95 each.
53:47Next time on NOVA,
53:49journey to Egypt for the classic struggle
53:51of mason versus stone.
53:53Obelisk on Secrets of Lost Empires.
53:57¶¶
54:00NOVA is a production of WGBH Boston.
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