For Pittsburgh resident Mike Neilson, proprietor of Used to Be a Pizza Hut, the iconic hump-roofed structure brings back happy memories of growing up the 1980s in the suburbs of Harrisburg, Pennsylvania. Back then, Pizza Hut pizza was "the de facto standard," he says, to be eaten while playing tabletop Pac Man games. A few years ago, Neilson moved to Pittsburgh, where he works at a company that develops mobile apps. He immediately noticed that when people in his new home gave directions, they often used bygone landmarks to guide the way. "There are no instructions to go anywhere without 'turn at what used to be there,'" says Neilson. "Of course, I don't know what used to be there." But if what used to be there was a Pizza Hut, Neilson realized, you could recognize it by its form alone.