The Old Chappaqua Historic District is located along Quaker Road (New York State Route 120) in the town of New Castle, New York, United States, between the hamlets of Chappaqua and Millwood. It was the original center of Chappaqua, prior to the construction of the New York and Harlem Railroad and the erection of its station to the south in the mid-19th century. In 1974 it was recognized as a historic district and listed on the National Register of Historic Places.