The 10 most expensive houses in the world

The Penthouse, One Hyde Park, London

• Estimated Value - $225 million

The most ostentatious penthouse in the United Kingdom, One Hyde Park Penthouse, is located in London's most affluent district, Knightsbridge. It was an architectural project by Rogers Stirk Harbour + Partners, with interior design by the Candy brothers, that was completed in 2009. The Penthouse is a six-bedroom apartment with bulletproof glasses that oversees an impressive panoramic view. The buyer of this two-story apartment is still unknown. 

Mesa Vista Ranch in the Eastern Texas Panhandle

• Estimated Value - $250 million

The 65,ooo-acre ranch of T Boone Pickens includes a lodge, private airport, pub, an 11,000-square-foot bird-dog kennel with space for 40 dogs, a chapel, golf fairways and greens, and 20 man made lakes. In 2008, the oil conglomerate relocated his childhood home from Oklahoma to the ranch.

The Odeon Tower Penthouse in Monaco

• Estimated Value - $330 million

Designed by architect Alexandre Giraldi and developed by the Groupe Marzocco's this 35,000-square-foot apartment at the top of the Tour Odeon spans many floors and has its own elevator. The private opulence does not end there: This penthouse is pretty impressive, with a water slide from an upper floor into an infinity pool with 360-degree views of the surrounding countryside.

The One Bel Air in Bel Air, California

• Estimated Value - $340 million

The largest house in the United States, with approximately 100,000 square feet of living space and a price tag of $340 million, is officially coming to market after nearly ten years of construction and design work. Located on one of the highest promontories in the Bel Air neighborhood of Los Angeles, Nile Niami developed the property and  architect Paul McClean designed it. The house features 26 foot ceilings, 42 baths, 21 bedrooms, 5 swimming pools, and a 30-car garage gallery. Not to forget the  panoramic views of downtown Los Angeles, the San Gabriel Mountains, and the Pacific Ocean.

Le Palais Bulles, Theoule-sur-Mer, France

• Estimated value: $390 million

France takes yet another spot in this most expensive house list with the fabulous and a bit eccentric Le Palais Bulles. The Bubble Palace is a collection of round rooms that spill down a rocky cliff overlooking the Mediterranean Sea, designed by Hungarian architect Antti Lovag and constructed between 1975 and 1989. Lovag is a seaside estate with three swimming pools, many parks, and a 500-seat amphitheater on the hillside grounds, which was allegedly inspired by man's earliest dwellings in caves. Bubble Palace is currently owned as a vacation home by Italian-born French fashion designer Pierre Cardin and has hosted a variety of swanky events, including Dior's cruise collection showing in 2015 at an indoor/outdoor fashion show at the sprawling estate.

Villa Les Cedres, Saint-Jean-Cap-Ferrat, France

• Estimated Value: $410 million

The 18,000-square-foot, 14-bedroom estate is set on 35 acres of manicured gardens and named after the cedar trees on the property. It features an Olympic-size swimming pool, a large stable, and decadent interior fit for the home's Belle Epoque heyday. When it was put up for sale in 2017 for $410 million by Davide Campari-Milano S.p.A of the Campari Company, this mansion was considered the most expensive house on the market in the world. It was designed in 1830 and purchased in 1904 by Belgium's King Leopold II.

Witanhurst in London, England

• Estimated Value - $450 million

This Georgian Revival house, which stretches over 90,000 square feet and was designed in the early twentieth century, is London's second largest home. Witanhurst has 65 rooms, 25 of which are bedrooms. The Lost Prince, Tipping the Velvet, and Fame Academy are only a few of the big and small screen productions that have used the house as a filming location. It's London's second-largest family house, after Buckingham Palace.

Villa La Leopolda in Villefranche-sur-Mer, France

• Estimated Value - $750 million

This 11-bedroom, 14-bathroom estate is situated on 50 acres in France's Alpes-Maritimes department of the Cote d'Azur region and is owned by Lily Safra, the widow of Lebanese-born Brazilian banker Edmond Safra. Alfred Hitchcock's 1955 film To Catch a Thief was shot on the site, which includes a commercial greenhouse, helipad, outdoor kitchen, and stunning pool. The estate was given to King Leopold II of Belgium's mistress, Blanche Zelia Josephine Delacroix, in the early twentieth century, and is now known as Villa La Leopolda. In the 1920s, American architect Ogden Codman, Jr. renovated the building.

Antilia Tower in Mumbai, India

• Estimated Value - $1-2 billion

Indian Billionaire Mukesh Ambani's home the Antilia Tower in Mumbai takes the second spot in this list with an estimated value of somewhere between 1-2 billion USD. This 27-story, 400,000-square-foot residence in Mumbai's Cumballa Hill neighborhood was designed in collaboration with Chicago-based architecture firm Perkins & Will and Santa Monica-based hospitality design firm Hirsch Bedner Associates. The tower has six floors dedicated to car storage, a car service station, a mosque, a 50-seat movie theater, and nine high-speed elevators, and can withstand an earthquake of magnitude eight on the Richter scale.

Buckingham Palace in London, England

• Estimated Value - $2.9 billion

The Queen of England's London residence still retains the distinction of most luxurious house in the world. With 775 rooms, 52 royal and guest bedrooms, 78 bathrooms, and 92 offices, Buckingham Palace tops the list with an estimated value of  a whopping $2.9 billion. Buckingham Palace has been the monarchy's official residence since 1837, despite the fact that the British Crown's trust controls several castles and estates in the United Kingdom.