A friend sent me this link from the Paleo-Future blog; it's pretty cool. The Capitol building used to have a really awesome monorail system. Today, in the passageway between the Capitol and one of the Senate office buildings (the Hart building, maybe?), you can still see one of the original cars. They've replaced the monorail with a more modern trolley thing, which saves congresspeople from any of the office complexes the time and energy of walking.
Here are some photos of the original, courtesy of the Paleo-Future post: