What makes a building inviting?

It rained again last night, and I visited a building near to me.

I am very familiar with this building and this building has been the home for some insightful ideas.
But, as I walked up to the building, I had a question:
What makes a building inviting?
Is it the door of the building?
Is it what is known to happen inside the building?
Is it the flowers that greet the visitor outside the building?


What do you think?