A painting by Dutch abstract painter Piet Mondrian has been hanging upside down for 77 years, says a curator at the German museum. Photo:AFP

A painting by Dutch abstract painter Piet Mondrian has been hanging upside down for 77 years, says a curator at the German museum. A large retrospective of the avant-garde artist's work went on display, and one of the pieces on show is "New York City 1," painted in 1941.

"In a photo from 1944, I saw that the canvas was the other way around on an easel. It intrigued me," the curator said, adding that the error could have been made because "the painting doesn't have a signature."

Mondrian, born in 1872, was a noted exponent of the 1920s abstract art movement known as "De Stijl" and was one of the most influential figures in modern art in the 20th century. His most famous artwork is Victory Boogie Woogie, considered one of the most important artworks of the 20th century.