Concrete ship Palo Alto and the pier at Aptos, California

The Palo Alto was built of concrete in an attempt to supplement shipbuilding while steel was in short supply during World War I. But, it wasn't completed until after the war; eventually it was sold, put at the end of pier in Aptos, California, and used for two years as an entertainment complex and den of illicit activities during the 1930 -- 1932 portion of the prohibition era. Damaged by storms, now it works as a breakwater and fish habitat.