The former World #1 professional tennis player summers here. The 10-bed, 12-bath (and 3-1/2 baths), 43,000 sq ft estate sits on 450 acres. He decided to sell after he was unable to get permits to build a high-end golf course on the land in 2005. He purchased the property in the late 1980's for $4.2 million, had the mansion built in 1992, and now has it on the market for $25 million, which includes a half interest in an additional 230 acres that are jointly held with a neighbor. Additional amenities include a 1,872 sq ft gymnasium with 25-foot ceilings, a separate spa and workout room with his-and-her steam rooms, locker looms, a game room, indoor and outdoor pools, a caretaker's house, a horse barn, formal gardens, and of course, state-of-the-art tennis courts.