RM Auctions are teaming up with Sotheby's to offer a rare 1963 ATS 2500 GTS 3.0-litre sports car at their Automobiles of London event, on October 28.
It will be the first time one of these highly desirable and extremely rare cars has been offered at auction.
The estimate is £600,000-£1m.
The car is one of only eight ATS sports cars produced between 1962 and 1965. This example - chassis number 004 - will be offered without reserve.
ATS - or Automobili Turismo Sport - has immense historical significance.
The Italian car maker and racing team was formed by Carlo Chiti and Giotto Bizzarrini (both of Ferrari GTO fame).
They established the company to directly compete with their former employer, Ferrari.
The ATS 2500 GTS made its debut at the 1963 Geneva Motor Show. Although 12 chassis were produced, only 8 cars were ultimately completed, making each a rare collector's item.
"We are thrilled to be offering this extraordinarily rare A.T.S. sports car at our upcoming London sale," said Max Girardo, Managing Director of RM Europe.
"Not only does our London event mark the auction debut for this particular example, but it's also believed to be the first time any ATS has ever been offered publicly at auction.
"As such, it is set to draw considerable interest from discerning collectors around the world as they contend for a very important and rare piece of ATS history," he added.
Serial number 004 is well-known to connoisseurs for its sleek bodywork and is believed to have been the last car assembled as well as one of only five surviving examples of the original eight.
Additionally, it is the only known 3.0-litre GTS example built in steel with the rare four dual down-draft 38 IDM Weber Carburettors.
It was originally the personal property of Count Volpi when he left ATS, before passing into private ownership.
It has changed hands very seldom since and is offered for sale in truly outstanding condition with less than 10,000 original kilometres and having undergone a complete concours mechanical and body restoration.
Most recently, the car was displayed at the famous Pebble Beach Concours d' Elegance and has been invited to next year's renowned Villa d' Este Concours at Lake Como, Italy.
The Automobiles of London event will be held on October 28 at Battersea Evolution, London, England. A full day preview will be held on October 27 from 10.00am-5.00pm GMT, followed by the auction on October 28 from 3.00pm GMT.