Here is a sneak peak inside what is likely to become the world's most expensive flat.
Featuring bullet-proof windows, an air purifying system and a panic room, the penthouse apartment in central London is set to be sold for a world record £140million.
The two-floor penthouse flat at the One Hyde Park development in Knightsbridge also features an underground passage leading to the nearby Mandarin Oriental hotel.
Other homes in the development have already sold at record prices of £6,000 per square foot.
Enlarge World record: The luxurious interior of an apartment at Christian and Nick Candy's Knightsbridge development
That compares with the Kensington and Chelsea average of £1,214 and London wide average of £450.
The price reflects the growing trend of super-rich international buyers snapping up 'trophy properties' in the capital, attracted by the weakness of the pound.
Russian oligarchs, oil barons, Saudia princes and A-list stars are among those said to be buying the Candy brothers apartments.
Trevor Abrahamson, of estate agent Glentree Estates, told the London Evening Standard: 'This is a huge price but it's not surprising.
Enlarge High life: An artist impression of the interior of one of the penthouse apartments at One Hyde Park
'In the last six months we have sold more trophy properties than we have in the last two years. One minute there was an over supply and then there was a shortage. Prices are high.
'London has recovered much better than other prime markets around the world. It draws buyers from the most eclectic range of destinations and it will always be seen as the capital of capitals financially and culturally.'
Once One Hyde Park is completed and all the buyers have paid up, the whole block will be one of the most expensive residential locations in the world.
One Hyde Park, seen here from Sloane Street, is one of the most expensive residential areas in the world
The biggest group of buyers are Russian, making up a third of the total. A quarter of buyers are Middle Eastern, 20 per cent are British and the remaining 22 per cent is split equally between the European and American markets.
It is understood that SAS-trained guards and iris scanners provide extra security to the apartments, which are due to be completed in October.
Christian Candy's CPC Group bought the One Hyde Park site for £150million in 2004. It used to be occupied by a rundown Fifties office block called Bowater House.
The London skyline from the penthouse at One Hyde Park and, below, another of the luxurious reception rooms
Houses rather than flats tend to achieve the highest prices in London. Lakshmi Mittal bought his first property in Kensington Park Gardens in 2004 for around £60million but is now worth over £150million.
Next to London, the most expensive flats are to be found in New York, where before the 2007 crash a triplex penthouse in the Pierre Hotel, overlooking Fifth Avenue and Central Park, was on the market for $70million.
Asia's most expensive apartment was sold in June 2008 for $28.8million, an 80th floor penthouse minutes from Hong Kong's central business district. In Sydney a penthouse with views of the harbour and Opera House sold for 20million US dollars.
An aerial view of One Hyde Park, the four geometric buildings in the central foreground, with the Serpentine winding away behind it
Read more: Penthouse apartment in London set to be sold for a world record £140million | Mail Online