They've been verrry slowly demolishing this building about a half-block from my work. About a year ago, when I started my job, the open pit you see here was an ugly, seventies-style, ten-story building. They started at the top and took it down floor by floor until they finally ended up with a giant hole about negative three stories tall. Apparently, they weren't allowed to just dynamite the thing because it's located just a few blocks from the White House.
Anyway, the weird buttressing posts caught my eye, as did the leftover morsel of underground parking garage still stuck to them.