The painting British artist John Constable kept by his side until his death is to be offered for sale.
The Lock - one of the small group of monumental landscapes known as the Six Footers, which for many define the pinnacle of the artist's career - will be put up for sale by Sotheby's auction house in December.
It depicts a bucolic scene on the River Stour in the artist's native Suffolk and is estimated to be worth £8-12 million.
The masterpiece was treasured by the artist who kept it in his studio until his death in 1837 and singled it out for prestigious exhibitions.
A print by David Lucas propelled the scene to fame, making it one of the most familiar and celebrated images in British art.
Julian Gascoigne, Sotheby's senior British pictures specialist, said: "Constable's absolute mastery as a landscape painter is everywhere in this picture - in the vigour of the almost impressionistic brushwork, in the drama of the clouds and the changing weather, even in the movement of the grass in the fields and the sparkle of water as it cascades through the lock. It is one of those pictures that captivates, and the more one looks, the more one sees."
The last time the artwork was on the market was 1855, having remained in the same family collection for more than 150 years.
It is one of only three major paintings by Constable left in a private collection.
The painting will be exhibited around the world in Hong Kong, New York and Los Angeles, before leading the Old Master & British Paintings Sale on December 9.