After we dropped an atom bomb on Hiroshima, Japan, the U.S. government used the remains of that city as an engineering research project—a place to study what nuclear blasts did to physical structures, and how we could build homes, shops, and schools that would withstand nuclear war better than those in Japan did.
The photos taken by the United States Strategic Bombing Survey have survived to this day. Some of them are featured in a photo essay at the New York Times. The one I've posted here is the least disturbing of the lot.
Via Brain Picker