Arden is a historic estate outside Harriman, New York, the 450-acre remains of a much larger property originally assembled by railroad magnate Edward Henry Harriman. By the early 1900s, Harriman owned 40,000 acres in the area, half of it comprising the Arden Estate. The main house is at the top of a 1,300 ft (400 m) bluff in the Ramapo Mountains 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.