It is the only United States real estate wherein title derives directly from a land grant by the British monarchy. Gardiner's Island was originally a separate British Colony. The Dutch controlled Manhattan and western Long Island (Brooklyn), while Queens (including Nassau) and Suffolk were in dispute between Connecticut, Rhode Island, and Massachusetts. The Colony of New York did not yet exist.
The first Lord of The Manor, Lion Gardiner, was wise. Although he held title from the Crown he respectfully purchased the island from the Native American Montauks as well.
The Gardiners have, throughout their long stewardship, striven to keep the island unspoilt and undeveloped. The island is home to New York State's largest colony of ospreys, and is one of the few locations in the world where ospreys build their nests on the ground, as there are no natural predators of the osprey on the island. The island is a natural stop on the migratory flightway, and thousands of species of birds can be seen there year 'round.
Its structures include the oldest surviving wood-frame structure in New York state, a carpenter's shed built there in 1639. The island is also famous for its windmill, and for the Gardiner Manor House.
As a punishment to the Gardiner family, the British burned the Manor House. They left the rest of the island alone; however, during the War of 1812, they again occupied the island, again used it for interdiction, and again burned the Manor House.
Captain William Kidd, the notorious pirate, buried treasure on Gardiner's Island in 1699.
The current Gardiner Manor House was built after World War II.