Is this the ultimate mega-mansion? Inside Belgravia's spectacular new £25m home created from a townhouse and four-storey mews

A six-bedroom mega-mansion has been listed for sale for £25 million in one of London's most exclusive squares.

Set in Belgravia's prestigious Chester Square, named England and Wales' fifth most expensive street last year, the property spans a total of 7100 sq ft and is a veritable trophy cabinet comprising Italian marble, bespoke joinery, leather finishes and silk wallpapers.

Behind the imposing stucco-fronted Georgian façade typical of other homes in the square, the mansion actually connects the original townhouse with the four-storey mews behind it.

It's not first of its kind, but it is one of the largest - and it's been 18 months in the making.

The linked area between the two buildings is seamless, largely due to an earlier extension to the original townhouse that developers and co-founders of Residence One, brothers Nick and Ben Wilson, believe wouldn't be granted today.

The decor is as you'd expect in a high-spec home, it's opulent but comforting too, with plush carpets and a light palette.

Highlights include two outdoor terraces, a sunken pool, sauna, cinema and internal garage.

And if midnight cravings come calling but the downstairs fridge feels just too far, there's even a night kitchen on the fourth-floor...

Luxury on a grand scale: the floorplans

The Belgravia mansion is for sale for £25 million, through Savills.