The Sutro Baths was a massive saltwater swimming pool complex in San Francisco, built in 1894 by Adolph Sutro. It was once the world's largest indoor swimming pool establishment but faced financial struggles and eventually burned down in 1966. The ruins now stand as a historic site in the Golden Gate National Recreation Area, showcasing concrete walls, blocked-off stairs, and a tunnel. The baths also played a role in a civil rights battle in 1897 when John Harris sued Sutro for racial discrimination, marking a significant victory against segregation in public facilities.