Coolidge Estate, also called Huntwicke, is a five hundred seventy-one-acre former private estate in Topsfield, Massachusetts, now protected for conservation. With more than a mile along the Ipswich River, it ranks among the state’s largest privately held conservation areas. Its centerpiece is a twenty-four-room Georgian-style brick mansion designed by Phillip Richardson in 1921 for John L. Saltonstall, incorporating materials from the seventeen nineties Nathaniel Saltonstall house in Haverhill. The grounds also feature Olmsted firm landscaping, other buildings, and extensive gardens. Later owned by William A. Coolidge, the property passed to M.I.T. after his 1992 death, and a 2000 agreement secured it against development, though the main buildings had become vandalized, unsafe, and condemned by 2023.