Closed since 2017, the Western Penitentiary (or, more recently, State Correctional Institution—Pittsburgh) will have a hard time finding a buyer. It would perhaps make a fine mansion for an eccentric supervillain, but most real-world supervillains are dreadfully prosaic in their tastes.
Nevertheless, it is a masterpiece of prison architecture—aesthetically, at least. The architect was Edward M. Butz, and it was built between 1876 and 1882, with various later additions. It looks more like a prison than the Bastille did, and so we present it on Bastille Day, with the cheerful news that no inmates are imprisoned here, but the sad news that it may eventually have to be pulled down by a demolition contractor rather than a revolutionary mob.