Torre David in the center of Caracas is a 45-story unfinished office tower. When the developer died in 1993, and then the crash of the Venezuelan economy 1994, it lay empty for a number of years. People started moving into the abandoned shell about 8 years ago. It is now an enormously tall slum.
Photographer Iwan Baan gave a TED Talk (watch it below) last year showing unusual uses of buildings around the world. Here are some of his amazing photos of Torre David in Venezuela. There are also photos of a city on the water in Nigeria, a trash town in Cairo and carved caves in China.