Governors Island is a historically important island, roughly 172 acres, that sits off the southern tip of Manhattan. Throughout the years, the island has primarily served as a United States Army Post and United States Coast Guard Base, and even served as the meeting place for Ronald Reagan and Mikhail Gorbachev during the 1988 summit meetings.
Today the majority of the island is owned by the state of New York, aside from a few buildings and structures which are seen to by the National Park Service. The island is only opened seasonally, but if you are in New York when it's open you'll definitely want to check it out. Aside from its vast history, the island also offers an amazing view of the New York City skyline. The only way to access Governors Island is by ferry from southern Manhattan.