Nantucket Fallout Shelter, Massachusetts

This small bunker in Nantucket is located at a former Navy submarine surveillance base, which has been turned into a town park. It is often called the Kennedy Bunker,  assumed to be there to shelter President John F. Kennedy, if the bombs started falling while he was vacationing there, as he sometimes did (though the Kennedy Compound is located at Hyannis Port, on Cape Cod).  It is a corrugated steel half-tube, with two chambers, covered in a dirt mound, next to a baseball field.