Built in 1913, Grand Central Terminal is one of the few overground stations in New York. Nowadays the train isn’t used as frequently in New York, and the Terminal has become more of a tourist attraction and shopping area than its traditional use.
What is impressive is the main concourse, with the high ceilings painted in constellations of the night.
On 1st avenue, right on the far East side of Manhattan the United Nations buildings can be found. There is a aerial tram to go over to Roosevelt Island in about 30 minutes, however I didn’t do this -but maybe next time!