It’s never hard to miss the work of Piet Mondrian: strict horizontal and vertical lines, always in the primary colors blue, red and yellow.

Hanging it the right way around is another matter, it would seem. Curators in Germany have now admitted that a significant Mondrian work has likely been hanging upside down for decades.

Ahead of an exhibition marking the 150th anniversary of the birth of the Dutch avant-garde painter, curator Susanne Meyer-Büser laid out the evidence to justify her gallery’s decision to turn the well-known painting "New York City 1" around.

The announcement was made at a press conference for the anniversary exhibition starting on Saturday in the Kunstsammlung Nordrhein-Westfalen in the western city of Düsseldorf.

The 1941 painting "New York City 1" is both the high point and the end of the "Mondrian Evolution" show, which traces the artist’s striking development from landscape painter to master of abstraction based on 90 pictures.

The work in question, made of red, yellow, blue and black adhesive strips crossing horizontally and vertically, has been part of the NRW Art Collection’s holdings since 1980 – and has been hanging upside down the entire time.

In contrast to its sister painting in oil, which was created at the same time and is almost identical in size, and which hangs in the Centre Pompidou in Paris, the adhesive painting has been shown upside down since Mondrian’s death in 1944, Meyer-Büser said.

What is also striking is that in a photograph taken in Mondrian’s studio a few days after his death in 1944, the adhesive painting can still be seen in a different orientation on the easel. The denser stripes are on the upper edge and thus run exactly as in the oil painting in Paris.

The way the tape was applied also appears to corroborate her assumption, and Meyer-Büser believes that Mondrian applied the tape from top to bottom.

At the top of the painting he still had control over the strips and applied them with precision, she said. "Towards the bottom, the strips are slipping."

There, the strips have been cut off in an unclean way, so that half a centimeter is always missing.

However, the way the Düsseldorf gallery has hung the painting the hanging, the unclean edges are now at the top. The direction of the adhesive strips ultimately convinced the restorers, says the art historian. "So it is to be noted that the painting ‘New York City 1’ from the art collection is upside down."

The problem is that Mondrian had not signed the painting. Possibly it was only used as a study object.

The hanging error may have happened as early as 1945 when the painting was first exhibited at New York’s Museum of Modern Art, Meyer-Büser says.

In any case, the painting’s correct orientation has gone down in art history in one fixed way, says Meyer-Büser. The art collection will no longer turn the picture over.

"New York City 1" still leaves much open to speculation.

Throughout his life, Mondrian worked with reflections to sharpen his own and his viewers’ perception, Meyer-Büser explains. Ultimately, this piece of artwork is like a city map that can be turned around as needed. And just like the city after which it was named, it runs in all directions.

"Maybe there is no right or wrong way round at all?"