There's a brick building at the corner of P and 18th Streets near Dupont Circle that used to be an overgrown wreck. I first noticed it in the fall of 2003. The grass was tall and unmowed, and there was a bare, dead tree inside the fence. It seemed abandoned. For various reasons I was rarely in the Dupont Circle area between spring 2004 and fall 2006. But one day in fall 2006, I was waiting for a bus to arrive at the bus shelter immediately in...