A work of art by Dutch abstract painter Piet Mondrian has been hung upside down in various galleries for 75 years, an art historian said, quoted by the BBC.
Despite the recent discovery, the work, titled New York City I, will continue to be displayed upside down to avoid damage.
The 1941 painting was first exhibited at MoMA in New York in 1945.
How was the bug discovered?
Since 1980 it has been exhibited in the art collection of the German state of North Rhine-Westphalia in Düsseldorf.
Curator Susanne Meyer-Büser noticed the error when researching the museum’s new exhibition on the artist earlier this year, but warned that the painting could disintegrate if it was now hung right side up.
“Once we pointed this out to the other curators, we realized it was very obvious. It is very likely that the picture is the other way around,” she added, contacted by the BBC.
One of the greatest artists of the 20th century
A photo of the influential Dutchman’s studio, taken a few days after his death, shows the same painting placed on an easel in reverse.
The image was published in the American lifestyle magazine Town and Country in June 1944.
Mondrian, who was born in the Utrecht region of the Netherlands in 1872, is considered one of the greatest artists of the 20th century and a pioneer of the modern abstract style, minimalism and expressionism.