Sagtikos Manor is the oldest house in the Town of Islip. Its original structure was built in 1697 and expansions were completed in 1772 and 1902. Originally built by Stephanus Van Cortlandt, it was purchased in 1758 by Jonathan Thompson, who deeded the house to his son Isaac upon his marriage to Mary Gardiner in 1772. It stayed in the Thompson-Gardiner family through the mid-20th Century. Under British occupation for a time during the Revolutionary War, President George Washington slept at the house in 1790.