At least from what I've seen there never was all that much of a housing bubble here in Philadelphia. There certainly was some overexcited flippers who though they were going to be able to rehab buildings and sell them for absurdly inflated prices, and condo developers who thought similarly, but I'm not sure all that many properties actually exchanged hands at those crazy prices (probably some condos were snapped up by speculators).
On my way to Drinking Liberally yesterday I walked by this house, one I curiously wandered into during an open house when I was house hunting. It was a wee bit out of my price range, listed for I believe about $1.6 million at the time. It still hasn't sold, and can be had for the bargain price of $1,150,000.
