The Sutro Baths in San Francisco were at one time the world's biggest indoor swimming area (http://tinyurl.com/52w32s
). All that is left now is the ruins of the foundation, which is gradually being taken back by the sea and vegetation. I shot this one night around midnight. The exposure was 7 minutes or so. I put a small flashlight through one of the "windows" in the foundation and it illuminated the plants that are now taking over what is left of the building.
Info: 376 seconds, f/8, ISO 100, 33 mm