The Weeks Estate is a historic estate on U.S. Route 3 in Lancaster, New Hampshire. The 420-acre (170 ha) property is now a New Hampshire state park.
It was built in 1912 for John Wingate Weeks, U.S. Representative from Massachusetts and a Lancaster native. Weeks would later (1921-1925) be the United States Secretary of War. He was responsible for passage of the Weeks Act in 1911, allowing for the establishment of national forests in the eastern United States, including the White Mountain National Forest. The estate, located at the summit of 627-meter (2,057 ft) Prospect Mountain, affords 360-degree views of the surrounding countryside, from the White Mountains to the south and east, to the Green Mountains in Vermont to the west, and the Connecticut River valley to the north.
The property was given to the state of New Hampshire in 1941 by Weeks' children, and the building was added to the National Register of Historic Places in 1985.