March 14, 1896: On March 14, 1896, the Sutro Baths were opened to the public as the world’s largest indoor swimming pool establishment. The baths were built on the western side of San Francisco by wealthy entrepreneur and former mayor of San Francisco (1894–1896) Adolph Sutro. The structure filled a small beach inlet below the Cliff House, also owned by Adolph Sutro at the time. Both the Cliff House and the former baths site are now a part of the Golden Gate National Recreation Area, operated by the United States National Park Service. The baths struggled for years, mostly due to the very high operating and maintenance costs. Shortly after closing, a fire in 1966 destroyed the building while it was in the process of being demolished. All that remains of the site are concrete walls, blocked off stairs and passageways, and a tunnel with a deep crevice in the middle. The cause of the fire was arson. Shortly afterwards, the developer left San Francisco and claimed insurance money.
The following statistics are from a 1912 article written by J. E. Van Hoosear of Pacific Gas and Electric. Materials used in the vast structure included 100,000 sq ft (9,300 m2) of glass, 600 tons of iron, 3,500,000 board feet (8,300 m3) of lumber, and 10,000 cu yd (7,600 m3) of concrete.
The baths were once serviced by a rail line, the Ferries and Cliff House Railroad, which ran along the cliffs of Lands End overlooking the Golden Gate. The route ran from the baths to a terminal at California Street and Central Avenue (now Presidio Avenue).
During high tides, water would flow directly into the pools from the nearby ocean, recycling the two million US gallons (7,600 m³) of water in about an hour. During low tides, a powerful turbine water pump, built inside a cave at sea level, could be switched on from a control room and could fill the tanks at a rate of 6,000 US gallons a minute (380 L/s), recycling all the water in five hours.