Debris clogs the entrance to the old cemetery vault in Georgetown, broken wine bottles, food wrappers, a tattered sleeping bag and pillow, household goods left by homeless people who sleep there on frigid nights. The tiny 8-by-8-foot brick cell looks the same as it did two centuries ago, when it was used to store corpses headed for the nearby cemetery. Daylight seeps through tiny peepholes in all four walls. Ivy and overgrown grass shield the cell from intruders' eyes. Just as homeless men and women find refuge there now, historians say, slaves once sought temporary sanctuary inside the dark v...
