18. (TIE) This Palladian-style mansion sits within the guard-gated Bradbury Estates near Los Angeles, and encompasses a whopping 30,000 square feet of space.
Price: $78 million
An extensive list of jaw-dropping amenities include a two-story library, infinity pool, 15-person spa, 10-car garage, 3D theater, poker lounge, and wine cellar for 2,000 bottles.