Nassau Hall is a historic mansion on the grounds of the Muttontown Preserve in the Village of Muttontown in Oyster Bay, New York. It was built in 1904 for Bronson Winthrop and was known as Muttontown Meadows. It was the first commission of Delano & Aldrich in the area. Its exterior walls were modeled after Mount Vernon, George Washington's home and it was on an estate of 183 acres.