A masterpiece of his David Hockneywhich hasn’t been shown in four decades, is set to sell for around £16m ($20.3m) at an auction organized by Christie’s house.

The 1965 work, “California“, has been in the same private collection since 1968 and was unveiled last Wednesday at the auction house’s London headquarters.

The project will be presented at Paris and the New York and will return to London for the auction held on March 7.

“David Hockney’s swimming pool paintings have become some of the most iconic and beloved images of our time,” said Kathryn Arnold, the auction house’s head of post-war and contemporary art.

The work is an extraordinary painting created shortly after Hockney’s first trip to Los Angeles in 1964, where he marveled at the brilliant light and mosaic-like cityscape filled with bright blue pools, he explained.

For Hockney, who grew up in northern England and studied in London, shaken by World War II, California must have been like Eden, a beautiful place to be free and enjoy youth, he added.

The work has been owned by a private European collector since 1968 and was last shown publicly in 1979.