A German museum has discovered what it believes to be a previously unknown work by German Expressionist artist Ludwig Kirchner that languished in its cellar for decades.

The Staedel Museum announced the find on Tuesday, saying that it had discovered it as part of renovation. The canvas is painted on both sides, with a rare nude, believed to have been painted in 1910, on the back.

The Frankfurt museum plans to restore the work and put it on display for the first time when it reopens in the fall of 2011. It did not give an estimate of the painting's value....