The 117,000 sq ft property was designed in the early 19th century by famed British architect John Nash, whose best-known designs include Buckingham Palace, Marble Arch and Brighton’s Royal Pavilion.

Overlooking London’s leafy Regent’s Park, the 28-bedroom mansion is believed to be the first entire John Nash-designed terrace to ever come to the open market.

(Related: Lessons that have helped Darius Cheung grow 99.co to be one of the largest property portals in the region)

This Grade I-listed building has planning permission to be turned into two houses and 26 apartments with 42 underground parking spaces, according to London-listed real estate adviser Savills Plc.

The mega mansion is offered on the market by real estate investment group Zenprop, which acquired the ultra-prime residency from the International Students Trust in 2016.

Despite the nine-figure asking price, Zenprop is reportedly hoping to sell 1-18 York Terrace East to an individual looking to acquire a private residence, rather than another developer.

“Nothing on this scale in such a prime London location has ever come up for sale. It is an opportunity to create a special and extensive private estate within the tranquil surrounds of Regent’s Park, moments away from Marylebone High Street and the West End,” Stephen Lindsay, head of Savills St John’s Wood, commented in a statement.

If the mega mansion sells for its asking price of £185 million, the transaction will be one of the most expensive in the history of Britain’s real estate market.

The Regency property would be second only to a 20-bedroom Knightsbridge mansion, which sold for more than £200 million back in January.

“It won’t appeal to many people, but we only need one person. The kind of person with billions, who wants a place in London,” Derrick Beare, CEO of Zenprop, told Financial Times, adding that he expects to attract prospective buyers from Asia.

(Related: The luxury hotel group Six Senses is to open in London)

Photo: Joas Souza/Savills