One of Hitler’s photo albums of art stolen by his Nazi troops during World War Two will be donated to the National Archives in Washington, DC, reports the Washington Post.

The Einsatzstab Reichsleiter Rosenberg unit of the German army looted artwork from homes and museums all throughout Europe during the war, carefully documenting their finds to keep Hitler abreast of their activities. According to Greg Bradsher, a senior archivist at the Archives, the albums were “not necessarily for him to look at and say, ‘Oh, I like that. I want it.’ It was more: ‘Here’s what we’re doing, boss.'”

During the war, 39 of these so-called “Hitler albums” were discovered by American forces and turned over to the Army’s Monuments, Fine Arts, and Archives program. Nicknamed the Monuments Men, the unit, which was the subject of this year’s George Clooney film of the same name, was dedicated to preserving cultural heritage and recovering artwork stolen during the war.

The photos became evidence during war trials and helped establish ownership of stolen art. The initial cache of albums became part of the Archives collection in 1947, and three more have been donated in recent years.

According to a press release from the Monuments Men Foundation, which works to preserve the program’s legacy and is facilitating the donation from a private downer, this is the last-known album of its kind (originally, it was a set of about 100 albums). It was recovered from Hitler’s Berchtesgaden home near the end of the war, and is full of photographs of paintings and other cultural items.

The photo album will be turned over on May 8, to coincide with the anniversary of the war’s end in Europe.