A new Vincent van Gogh painting has been discovered—underneath another van Gogh painting. Patch of Grass, the artist’s 1887 landscape that was painted over the hidden portrait of a woman is housed at the Kroller-Muller Museum in the city of Otterlo, Netherlands, according to NPR.

Van Gogh recycled his own canvases, as do many artists, which made the portrait visible through x-ray technology. The portrait was discovered by scientists at the University of Antwerp in Belgium and Delft University of Technology in the Netherlands. Check out the NPR story to watch a video that takes you inside the x-ray process.