A housing development in St. Louis, MO, built in 1955. It was intended for the "deserving poor," but wound up with the even poorer. The buildings were of atrocious quality, with corners cut everywhere to keep costs down. Locks broke on first use, an elevator failed on opening day. The place was a mess from day one. It wound up being occupied almost exclusively by very poor black families (attempts were made to integrate one of the buildings, but it didn't work), most of them welfare-dependent, many with no wage earner in the family, lots and lots of children... basically a tenement, or worse.
The buildings were dynamited in 1972. They were just an astounding failure. The project is now held up as a prime example of poor planning and execution in urban housing. Architects also muse about it, talking about how the architecture was somehow responsible as well; I don't pretend to understand that aspect properly. Search for it online.
I think this project is also the basis of the title of a track from Philip Glass's album and movie, Koyaanisqatsi, though that track is (mis?)spelled "Pruit Igoe."