Like stamps on a passport, the stamps on these captured Russian military maps tell a story—for the maps, it's often one of intrigue and globetrotting. Stamps emblazoned with national insignia reveal that some of these secret maps were captured by the Nazis and others by the U.S. Army during World War II. Several maps bear stamps suggesting they passed through the hands of multiple foreign military and intelligence agencies.

The maps are part of a collection of 4,000 Russian military maps at Indiana University. They were made between 1883 and 1947, and they were never meant to be seen by outsiders, says IU map librarian Theresa Quill. Many are marked “СЕКРЕТНО” (SECRET) or “НЕ ПОДЛЕЖИТ ОГЛАШЕНИЮ” (NOT SUBJECT TO DISCLOSURE) in