Who owns the most expensive house in the world? 
With 775 rooms, including 52 royal and guest bedrooms, 78 bathrooms, and 92 offices, the Queen's luxurious London home still holds the top ranking for the most expensive house in the world, most beautiful, biggest and most amazing. 

The next most expensive building in the world is Antilia, designed in consultation with Chicago-based architecture firm Perkins & Will and Santa Monica-based hospitality design firm Hirsch Bedner Associates, this mega luxury residence is owned by Indian billionaire, Mukesh Ambani.

What makes these homes so expensive?
For those who are listed as the richest people on Earth, there’s more to a ‘home’, than just modesty and utility, it's all about 'fancy mansions'  or rather, real estate.

To these, who ace the lists of ‘Forbes’ Top Billionaires’ and ‘The Most Expensive House In The World’, home is a place where they can spend most of their fortune, afford unimaginable luxuries and flaunt their wealth.

For example, If you take a quick tour inside Donald Trump’s house, You’ll find nearly everything in gold. Also, The Bill Gates’ house where he has screens that display any desired painting, photo or artwork that cost $150,000.

These billionaire homes are architectural expressions born out of extravagance and vanity. That or their historically monumental driving that price tag up another billion.

Their lavishness and exclusivity not only inspire commoners towards riches but also provide opportunities for experimentation, with some of the most expensive and uncommon technological innovations.

This is a list of the top 5 most expensive houses in the world:

1. Buckingham Palace, London

Estimated value: $2.9 billion

With 775 rooms, including 52 royal and guest bedrooms, 78 bathrooms, and 92 offices, the Queen's London home still holds the top ranking for the most expensive house in the world. Although the British Crown's trust owns many castles and estates throughout the United Kingdom, Buckingham Palace has been the monarchy's official residence since 1837. Queen Elizabeth II spends her annual summer holiday at Balmoral Castle in Scotland's Highlands.

2. Antilia Mumbai India

Estimated value: $1-2 billion

Designed in consultation with Chicago-based architecture firm Perkins & Will and Santa Monica-based hospitality design firm Hirsch Bedner Associates for Indian billionaire Mukesh Ambani, this 400,000 square-foot residence in Mumbai's Cumballa Hill neighborhood is 27 stories high. The tower, which can sustain an earthquake of magnitude 8 on the Richter scale, features six floors devoted to car storage, a car service station, a temple, a 50-seat movie theater, and a nine high-speed elevators.

3. Villa Leopolda, Villefranche-sur-Mer, France

Estimated value: $750 million

Owned by Lily Safra, widow of Lebanese born Brazilian banker Edmond Safra, this 11-bedroom, 14-bathroom estate is perched on 50 acres in France's Alpes-Maritime department of its Cote d'Azur region.

It features a commercial greenhouse, helipad, outdoor kitchen, and stunning pool, and was the setting for Alfred Hitchcock's 1955 film To Catch a Thief. Villa La Leopolda is named for its original owner: King Leopold II of Belgium gifted the estate to his mistress Blanche Zelia Josephine Delacroix in the early 20th century. The home was redesigned by American architect Ogden Codman Jr. in the 1920s.

4. Witanhurst

Estimated value: $450 million

Built in the early 20th century, this Georgian Revival mansion is the second largest residence in London, clocking in at over 90,000 square feet. There are 65 rooms, including 25 bedrooms. The house has been used as a filming location for large and small screen productions, including The Lost Prince, Tipping the Velvet, and Fame Academy.

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

Estimated Value: $410 million

Built in 1830 then purchased in 1904 by Belgium's King Leopold II, this mansion was considered to be the most expensive house in the world on the market, when it went up for sale in 2017 for $410 million by Davide Campari-Milano S.p.A of the Campari Group, the property's current owner. Set on 35 acres of manicured gardens and named for the cedar trees on the grounds, the 18,000 square-foot, 14-bedroom estate boasts an Olympic-sized swimming pool, a large stable, and decadent interiors (think ginormous crystal chandeliers, intricate gilded woodwork, and 19th century oil paintings) fit for the opulence of the home's Belle Epoque heyday.