The Mayfair home of former Lincoln MP George Fieschi Heneage is on the market - for a staggering £50million.
The Grade II listed mansion has spent years in decline and is now a wreck, requiring a full refurbishment. It is estimated that a further £20million is required to restore it to its former glory.
But the terraced property sits in the middle of London's Mayfair, one of the most desirable locations in the world, and is expected to attract keen interest from billionaires.
Heneage was MP for Lincoln between 1831 and 1835, and again between 1852 and 1862.
The super-rich are looking at trophy homes in the same way they see mega-yachts and are playing wealthy games of one-upmanship.
And 39 Charles Street could be transformed into one of the UK's finest city homes worth a staggering #100 million after renovation.
The mid-18th Century home will boast seven palatial bedroom suites, eight state rooms, a leisure complex and private cinema when completed.
The main bedroom suite will be spread across 2,000 sq/ft, which is twice the size of the average new UK home, and includes his and hers dressing rooms and bathrooms.
There will an eight person lift, a mews home for guests or staff, a wine room, office, catering kitchen and a number of high security vaults.
The property currently has listed Chinese wallpaper and silk wall mountings which will be removed and reinstated as part of the refurbishment.
It has been put up for sale with estate agent Wetherell for a jaw-dropping £50 million. Beauchamp Estates is also marketing the property.
This is more than 300 times the average price of a house sold in England and Wales - and the price could end up rising with the possibility of offers coming via sealed bids.
Whichever billionaire wins the battle for Charles Street will then have to spend #22 million restoring it.
But on top of the glamour of owning one of London's finest homes, buying Charles Street could also be a savvy investment.
When completed, the mansion will be worth in excess of #100 million - and this value could DOUBLE within the decade with prices expected to skyrocket in Mayfair.
Peter Wetherell, managing director of Wetherell, expects four types of people to look at the home - Oil royals, African moguls, billionaires and property developers.
He said: "£50 million is a lot of noughts and bandying out this figure willy nilly needs a lot of thought given to why someone would even wish to spend this much on one property.
"The key features of these #50 million-plus homes are opulent state rooms, princely proportions and every leisure facility and luxury imaginable.
"Everybody knows each other, and as they also do with their mega-yachts, the competition and rivalry to create the world's best trophy houses is immense.
"We anticipate a fierce battle by super-rich bidders to snap it up. Once converted it will be one of London's most outstanding mansions."
Mr Wetherell added he recently sold a 'fixer-upper' for £20.5 million after it was initially marketed for £18 million.
The £50million home on Charles Street is thought to have been built after 1750 by John Phillips and George Shakespeare after entering an agreement with Lord Berkeley of Stratton whose ancestors had acquired the land during the reign of Charles II.
Previous residents have included Heneage, The Earl of Camperdown (1867-1918) and The Marquis of Anglesea in 1920.
After World War Two, 39 Charles Street - like many Mayfair properties - was converted to commercial use.
But the area is undergoing its biggest overhaul in 100 years, with these grand properties being converted back into homes for the super-rich.