A painting by the world-renowned landscape artist John Constable has gone on display after it underwent 270 hours of cleaning.
The Embarkation of George IV from Whitehall: the Opening of Waterloo Bridge, 1817, was now back to its "full glory", the National Trust (NT) said.
It now looks like it was painted at a "different time of day", it added.
The work has been rehung at the NT's Anglesey Abbey, in Lode, Cambridgeshire.
The large painting by the Suffolk-born artist records the scene on the River Thames in London on the second anniversary of the Battle of Waterloo. It is now on display in the Abbey's library, where panels and shelves are made from timber salvaged from the piles of the original Waterloo Bridge when it was dismantled in 1936.
The charity said the work takes centre stage in an exhibition, Constable Revealed, that has opened at the property and will be on show along a painting called Summer Evening, Stoke-by-Nayland which has now been acknowledged as an original Constable work.
Referring to the depiction of Waterloo Bridge, the charity said: "The largest known painting by artist John Constable, but which was never exhibited in his lifetime, has been brought back to its full glory by National Trust conservators, revealing a long-vanished Thames skyline view."
The artwork was sent to the NT's Royal Oak Foundation Conservation Studio in Kent, where "several layers of badly yellowed varnish had obscured the detail and turned the painting into a very dulled view of the 19th Century Thames", it added.
It has now been transformed to show "bright blue skies".
Sarah Maisey, senior remedial conservator for paintings at the NT, said there were "challenges" during the restoration.
"There had been some earlier tests which showed that this painting would respond really well to varnish removal but it has been a particular delight to see the quality of the improvement.
"It had been painted, and varnished, at different stages so care had to be taken to ensure that the solvents being used to thin and remove the varnish layers didn't also affect the paint layer.
"We are delighted with the final result."