Reid Hall, also known as "The Castle", is a historic academic building located on the campus of Manhattanville College at Purchase, Westchester County, New York, United States.

The Renaissance Revival structure was built in 1892 as a 50,000 sq ft (4,600 m2) private home for publisher and diplomat Whitelaw Reid, with estate landscaping by Frederick Law Olmsted.

The Castle was designed by Stanford White and built in 1892 as a dwelling for Whitelaw Reid after he returned from Paris after serving as the 28th United States Minister to France.

The building was expanded in 1912 by McKim, Mead & White with a large library wing and guest cottage.

It features a five-story tower and a corbelled battlement parapet that conceals a flat roof.