The Sutro Baths were built in 1896 in San Francisco, California. This swimming complex was the largest in the world. Located on the west side of San Francisco bordering the Pacific Ocean, it was built and owned by the then San Francisco mayor, Adolph Sutro. The Baths were built of glass, iron, wood, and reinforced concrete with pumps in the nearby cavern that could pump the ocean’s water into the building and fill the 6 salt-water pools.
These 6 pools had different temperatures while there was one fresh water pool. When the pumps were activated they could fill the tanks at a rate of 6,000 US gallons a minute (380 L/s), recycling all the water in five hours. When there was a high tide 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. There also existed a museum where visitors could view Sutro’s personal collection as well as a collection of stuffed and mounted animals.
Due to its large cost to maintain and to operate, the baths struggled for years before finally closing in 1966. Unfortunately, in the same year it closed, the baths burned down and left behind only ruins of the baths and a large crevice.