This past March, the Fleur de Lys Mansion sold for $102 million, making it the highest-priced home sale to date in Los Angeles County. It was first listed in 2007 when original owners David and Suzanne Saperstein finished renovating the manse, divorced and moved out. The current owner, who paid entirely in cash and has chosen to remain anonymous, is rumored to be former junk bond king Michael Milken, according to the L.A. Times. The 12-bedroom, 15-bathroom home, which was modeled after the French castle Vaux le Vicomte when it was built in 2002, has a 3,000-square-foot wine cellar with a tasting room, two-story library, commercial kitchen, cutlery room and spacious ballroom. The property also features a pool, spa and tennis courts. It was used for the film "The Green Hornet," the ABC TV series "Big Shots" and the 2008 Audi Super Bowl commercials.

Indian steel tycoon Lakshmi Mittal calls this Kensington Palace Gardens home his "Taj Mittal." He bought it for £57 million -- about $89.4 million in today's dollars -- from English business magnate Bernie Eccclestone in 2004. The estate's nickname is only sort of a joke: Mittal renovated it with marble that was sourced from the same quarry as the actual Taj Mahal. The property is on the tree-lined "Billionaires' Row," where other highly affluent people like Roman Abramovich and Leonard Blavatnik also own property. It has 55,000 square feet of space, 12 bedrooms, a Turkish bath, swimming pool, picture gallery and ballroom.

Antilia, a 27-story skyscraper on the pricey Altamount Road in Mumbai, is the most expensive home in the world, valued at upwards of $1 billion. Mukesh Ambani, an Indian business tycoon and multibillionaire, moved into the 400,000-square-foot mansion in 2012 with his wife and three children. The modern property was designed by Chicago-based architects Perkins & Will. Antilia, which was named for a phantom island in the Atlantic, features a multistory garage with space for 168 cars, a ballroom, three helipads, gardens, a temple, guest suites, a health level and a home theater that seats 50.

Bill Gates, Microsoft co-founder and the world's second-richest man, took seven years to custom-build Xanadu 2.0, a modern-yet-rustic, high-tech estate valued at $125.5 million. According to luxury website The Pinnacle List, Gates bought the lot in 1998 for $14 million. It's named after the home of the title character in "Citizen Kane." The 66,000-square-foot "smart" complex is built into the side of a hill and looks out over Lake Washington. Electronic pins worn by residents and visitors trigger their personal preferences, like the temperature and lighting of a room or even the art that will appear on high-definition monitors throughout the property. It features a 3,900-square-foot pool building, 2,500-square-foot gym, a 2,100-square-foot library with a dome ceiling, a 2,300-square-foot reception hall, a 6,300-square-foot underground garage and many other amenities.

Real estate mogul Jeff Greene just listed his 25-acre estate in Beverly Hills for a heart-stopping $195 million, earning the property the honor as the country's most expensive listing. The Palazzo di Amore is a Mediterranean-style villa that tops 53,000 square feet of space, though 15,000 of that is an entertainment complex containing a ballroom with a revolving dance floor. It has 12 bedrooms, 23 bathrooms, a bowling alley, a theater, tennis courts, swimming pools, reflecting pools, waterfalls and a garage that can comfortably fit 27 cars. The property can accommodate parties for up to 1,000 people, who can spend their time meandering the gardens and vineyards where the property produces its own wine, or walk over floating glass walkways hovering above pools lined with mature olive trees.

Fair Field, a 63-acre oceanfront compound in The Hamptons, is valued at around $248.5 million. It's owned by billionaire investor Ira Rennert, who started building the sprawling estate in 1999 but couldn't move in with his family until 2004 after plowing through some nasty neighborly controversy. Nearby residents complained about the project to the Town of Southampton in 1998, claiming that a 110,000-square-foot home would have a negative impact on the neighborhood. After their lawsuit failed, Rennert built the home anyway, but now Southampton homes can't be more than 20,000 square feet. Fair Field has 29 bedrooms, 39 bathrooms, its own power plant, three swimming pools, a synagogue, two courtyards, an orangery, a 164-seat home theater, basketball court and bowling alley.