Arden is a historic estate outside Harriman, New York, that was owned by railroad magnate Edward Henry Harriman and his wife, Mary Averell Harriman. By the early 1900s, the family owned 40,000 acres (63 sq mi; 160 km2) in the area, half of it comprising the Arden Estate. The main house is at the top of a mountain east of the village, reachable by Arden House Road from NY 17. Since 2011, it has been owned by the nonprofit Research Center on Natural Conservation, which operates Arden House as a conference center with 97 guest rooms.