A view of the River Thames painted by Claude Monet has sold for almost £18m - more than twice its estimated price.
The painting had been predicted to fetch between £6-£8m
An anonymous telephone bidder paid £17,940,000 for Waterloo Bridge, Temps Couvert during a sale at Christie's auction house in London.
The sale - the second highest price fetched for a Monet - kicked off a week of huge sales on the London art market.
Monet's Nympheas, an iconic image of water lilies, is expected to make £10-£15m at auction on Tuesday.
It is one of only a few of the lily paintings still in private hands, and will go under the hammer at Sotheby's as part of the auction house's impressionist and modern art sale.
The sale will also feature works by Henri Matisse, Pierre-Auguste Renoir and Pablo Picasso.
Waterloo Bridge, Temps Couvert is one of a series of views of the bridge and river that Monet painted from his room at the Savoy Hotel around the start of the 20th Century.
Another Monet, the water-lily painting Les Arceaux de Roses, Givenchy, sold for £8,980,000 on Monday, just below its pre-sale estimate.
Bobby Read, an expert at specialist insurer Hiscox, said the sale showed the art market was "going from strength to strength."
"With paintings that have not been seen in public for 40 years this was always going to be a great sale," he said.
"Paintings like the Monets sold at Christie's are few and far between."
The total sum raised by the impressionist and modern art auction was £121,127,200.
Jussi Pylkkanen, president of Christie's Europe, said: "The sale at Christie's was a landmark event in the history of the art market, realising the highest total for any auction ever held in Europe."
On Wednesday, Christie's holds a contemporary art sale that includes Lucian Freud's portrait of Bruce Bernard.
Billed as the most important Freud work to appear at auction, it is expected to break the current record for the artist at auction of £4.2m.