It's a sad fact of life as a building that, eventually, you're going to wear out your welcome within the community. At that point, you have two options: be torn down or become something else. All of the buildings on this list chose the latter option, with insanely impressive results.
3China's Water Cube Becomes Happy Magic Water Park
Built for the 2008 Olympics in Beijing, the Water Cube was a bold statement to the world that, yes, the Chinese do know how to build structures that look like they're ready to hatch the next gigantic monster that will destroy every city in its path.
It was modern, beautiful and almost completely useless after the Olympics were over. That's when China came up with a radical idea: They would turn this former home of Olympics swimming into ... a water park.