From Wikipedia:

SS Atlantus is the most famous of the twelve concrete ships built during World War I.

The steamer SS Atlantus was built by the Liberty Ship Building Company and launched on December 5, 1918, just after World War I had ended. She made a number of trans-Atlantic crossings, returning troops home. After being decommissioned, she was purchased for civilian use in 1926. Her owner had plans to create a ferry dock (for a route now served by the Cape May-Lewes Ferry) out of her and two of her sister ships. She never saw service, however, as a storm ran the ship aground at Sunset Beach, New Jersey and she could not be freed.

At one time there was a billboard painted on the side of the ship advertising boat insurance. At present she remains a Cape May tourist draw, but her condition is rapidly deteriorating, with only her stern above water.