High in the Bavarian Alps, a white castle with soaring turrets overlays a scene of rolling green meadows and snow-capped mountains straight out of a storybook watercolor. The setting is so idyllic it served as Walt Disney’s inspiration for Sleeping Beauty’s castle.

But the world-famous Neuschwanstein Castle, nearly straddling the German-Austrian border, once played host to something more sinister than the fairytale setting it inspired. During World War II, the Nazis, aiming to amass a world-class art collection for Hitler’s dream of a “Führermuseum,” stashed thousands of paintings inside the castle. When the war ended, it also closed a 12-year period now recognized as history’s largest art heist—raking in priceless masterpieces from the likes of Michelangelo, da Vinci and Vermeer—and the recovery efforts were tasked to an allied unit known as the Monuments Men.

What began as a brain trust of the art world’s finest during the war became a group of 345 men and women from 13 countries that comprised the Monuments, Fine Arts and Archives Section unit. They spent 1945 seeking out more than 1,000 troves containing an estimated 5 million pieces of artwork and cultural items stolen from wealthy Jews, museums, universities, and religious institutions. And for six years after the surrender, a smaller group of about 60 Monuments Men continued scouring Europe as art detectives. Now, on Friday, and more than 70 years after the recovery began, a George Clooney-directed movie documenting their cultural reconnaissance opened in theaters with an all-star cast.