6. Fleur de Lys

Arguably the most expensive home in the United States, the Fleur de Lys in the exclusive Holmby Hills enclave of Los Angeles has been on the market since 2007. The price tag? An unapologetic $125 million [source: Coldwell Banker].

The 15-bedroom, 41,000 square foot (3,809-square-meter) mansion -- which was inspired by the 17th-century French Chateaux Vaux-le-Vicomte (itself an inspiration for Luis XIV's Versailles) -- was built by Texas billionaires David and Suzanne Saperstein, but ended up in Suzanne's hands after a nasty divorce involving a Swedish nanny [source: W Magazine].

Among its authentic Francophile flourishes, the home's exterior walls are covered with imported, handpicked French limestone. The interior is bedecked with 24-karat gold trim and museum-piece furniture like Napoleon's favorite chair and Marie Antoinette's personal curtain pattern [source: HGTV]. If you get bored, you can always watch a Jean-Luc Godard flick in the 50-seat screening room [source: Forbes].

Newlyweds Mariah Carey and Nick Cannon made a rumored bid for the mansion in March 2009, but it was still on the market as of October 2009.

The 19th century villa on the next page has come a long way from its former status as a girl's prep school.