The Queensboro Bridge, which provides both a ceiling and a name for this park, opened in 1909, connecting Manhattan and Queens by way of an intermediary link on Roosevelt Island, was once known as Welfare Island. The two-leveled steel bridge is one of eight New York City bridges that span the East River. Designed by engineer and architect Gustav Lindenthal (1850-1935), it is the first major structural project to reject the suspension technique in favor of cantilevering. The upper level once carried wooden railway cars, and five-cent trolleys shared the lower level with automobiles until 1955. In addition to his work on the Queensboro Bridge, Lindenthal prepared plans for the Manhattan Bridge, helped to complete work on the Williamsburg Bridge, and directed the reconstruction of the Brooklyn Bridge. The National Register of Historic Places added the Queensboro Bridge, also known as the 59th Street Bridge, to the list of City landmarks in 1978.