On one of my trips to San Fran, I happened to pass by a subway entrance one evening while heading back to the hotel after shooting a bit. I find subways interesting because we don't have them here in Texas - too much rock to dig through I guess. I also enjoy shooting trains so I headed on down the steps to underground San Francisco. It's cool being down there, especially at night when it is empty. I really enjoy the distant rumble of an approaching train, and the squeak of the brakes when it gets there. Aren't those just distinctive sounds?