Interpol agents have uncovered an enormous collection of what they believe are 75 original artifacts from the Third Reich hidden behind a bookcase inside a house in a Bueno Aires suburb, the Associated Press reports.

The Nazi collection, which agents believe is the largest ever to be found in the country's history, includes a wide range of artifacts including a statue of a Nazi eagle, Nazi toys for children, a bas-relief of Hitler, and a medical instrument likely used to measure people's heads. Police think the memorabilia originally belonged to top Nazis—and maybe to the Fuhrer himself.

Authorities started investigating the rare Nazi artifacts after they came across some suspicious pieces at a gallery north of Buenos Aires. The Argentinian federal police called in Interpol, who helped trace the Nazi pieces back to a private collector's house. After raiding the place, agents came across a book shelf that was actually the door to a secret room, because where else would you expect someone to hide a collection of rare Nazi gear?

Many of the pieces were paired with photographs of Hitler holding what appears to be the items. "This is a way to commercialize them, showing that they were used by the horror, by the Fuhrer," Patricia Bullrich, Argentina's Security Minister, told AP. "There are photos of him with the objects."

The collection's owner was not arrested, but an investigation is currently looking into any potential criminal activity. Authorities also hope to figure out how exactly the artifacts wound up in Argentina in the first place.

"Finding 75 original pieces is historic and could offer irrefutable proof of the presence of top leaders [in Argentina] who escaped from Nazi Germany," DAIA president Ariel Cohen Sabban told AP.

After WWII, South America became a refuge for former high-ranking Nazis fleeing persecution. Both "Angel of Death" Josef Mengele and Holocaust organizer Adolf Eichmann lived in Buenos Aires after the war, though it's not clear if those officials had any ties to the newly-discovered artifacts—let alone how the collection wound up behind a trick bookshelf in 2017.