Designed by Bloody Stupid Johnson, Empirical Crescent looks like a normal set of houses on the outside, but the dimensions inside are a little twisted. Someone might live at number 1, but their bedroom could be at number 3 and the kitchen in number 5. It is okay to throw your junk out the window because it probably doesn't land in your garden. The one main advantage residents have is the low crime rate. This is probably due to the fact that most thieves prefer to only break into one house at a time.
Despite the best efforts of the Ankh Morpork Historical Preservation Society the place still hasn't been pulled down (as of Thud!) and its unique properties have ensured that not only do people not stay very long (owing to the problems of living in such a place) but it also lowers the value of the area around it, kind of like having a sink estate beside a posh housing development...
Possibly a reference to Robert Heinlein's famous story, "--And He Built a Crooked House--"