9. United Nations
Constructed from 1948-1952 and designed by Le Corbusier and Oscar Niemeyer, the United Nations building is a sovereign nation. The design incorporates elements of William Zeckendorf’s Dream City to rival Rockefeller Center, which never came to be. In 1946, Nelson Rockefeller (John’s son) bought the East River property from Zeckendorf and donated it for use as the UN Headquarters. While on a visit, don’t miss the reopened Delegates Dining Hall open to the public.