Bed with a pool in world’s most expensive house

The mansion going on sale early next year is billed as the most expensive in the world and sprawls over a hilltop with 360-degree views of Los Angeles.

The largest of its 20 bedrooms will be a 5500 sq ft master suite, with its own office, pool and kitchen, a retreat for the billionaire owner when he or she has tired of floating in their four swimming pools, riding their five lifts or entertaining in their inhouse nightclub. The average British house covers just under 1000 sq ft.

The One, as the house is called, has been under construction for five years and is expected to be completed in the spring. At 100,000 sq ft the Bel-Air property will be among the biggest private homes in America. And if it sells for its US$500 million asking price it will be the most expensive.

Last year the Playboy Mansion in LA’s Holmby Hills sold for half its asking price of US$200m.

The highest price achieved in the United States is the US$137m that Barry Rosenstein, a hedge fund manager, spent on a spread in the Hamptons in 2014. The most expensive home ever sold in the world is believed to be a 54,000 sq ft modern French chateau near Versailles which is said to have sold in 2015 for US$301m.

The buyer’s name has not been revealed but according to The New York Times, the ultimate owner, through a series of shell companies, is Crown Prince Mohammed bin Salman of Saudi Arabia, who is leading an austerity drive at home but who has also been identified in the past year as the buyer of a US$500m yacht and a Leonardo painting for US$450m.

Nile Niami, 49, the developer of The One, is a former B-movie producer who was brought up by his mother, a special needs teacher, in an 1,100 sq ft home in Los Angeles.

He has already built more than 30 houses in the city, specialising in luxury speculative houses in affluent neighbourhoods. In 2012 he bought the hilltop site for The One for US$28m. He flattened the 10,000 sq ft house he found there, lopped the top off a hill to improve the views from the new property and brought in the architect Paul McClean to build it.

McClean, who also designed a Bel-Air home for which Jay Z and Beyonce paid US$88 million this year, said that The One would be as much an entertainment complex as a house.

Mr Niami imagines a buyer who already has four or five other homes and essentially wants a private hotel that they could visit a few times a year.

"They would have a full staff with uniforms," Niami said.

There is a separate on-site building with seven bedrooms for those staff, one of the many striking features of the property - along with a commercial-sized beauty salon and a lounge where the walls and ceilings are made of aquariums full of jellyfish.

Property experts think that Niami is extremely unlikely to get his asking price, but he could still make a vast profit.