Subways are interesting to me since we do not have them here in Texas. Maybe the rock is too tough to dig through, or we just didn't think ahead, but our trains are above ground. Come to think of it, there are lots of swimming pools so the rock can't be that tough. Anyways, while in Boston I took some shots of the subway entrance that was next to my hotel. I like the gritty, industrial feel of the place, and it is cool to hear the distant noises of trains moving about. Makes you want to hop on board and go somewhere.