4. Four Fairfield Pond -- $248.5 million 

Located in Sagaponack, N.Y., two villages over from ultra-chic East Hampton, this 29-bedroom estate has its own power plant, basketball court, bowling alley, squash courts, tennis courts and a 91-foot long formal dining room. Its owner, Ira Rennert, built his personal fortune of an estimated $5.9 billion through acquiring companies by raising junk bonds.