Cuban artist Tania Bruguera unveils installation at Tate Modern

Cuban artist Tania Bruguera unveils her latest installation at Tate Modern's Turbine Hall, the first in a series of pieces focusing on the crisis in migration. The installation - which requires the participation of gallery visitors - is made from a heat-sensitive material meaning the pieces can only be revealed by people collectively touching the floor, and demonstrates the artist's belief that people must work together to solve society's problems.