A plane over Cologne in WWII (Photo: 418th Bomber Sqaudron/Jodi Womack/Flickr)

Today, in Cologne, Germany, 20,000 people had to evacuate the city after a one-ton bomb from World War II was unearthed at a construction site. Anyone living within half a mile of the site where it was found had to evacuate; a nearby zoo was closed as well. All this added up to, the BBC reports, “the city’s largest post-war evacuation.”

During World War II, Cologne was regularly bombed—the Allies ran more than a thousand sorties against the city and dropped tens of thousands metric tons of bombs down from the sky. In 1942, in one night, the Royal Air Force sent 1,000 bombers to drop 1,500 tons of bombs on the city. By the end of the war, the population had shrunk from more than 750,000 to about 40,000 people.

It’s not at all unusual to find unexploded bombs in Germany. In 2011, the largest bomb disposal operation since 1945 dealt with two 1.8 ton bombs in Koblenz, where half the city’s population had to evacuate. This past November, 17,000 people were evacuated from the city of Dortmund when another 1.8 ton bomb was found. And in December, 10,000 people had to evacuate their homes near Berlin after a bomb was found near a main railway station. All told, there are thought to be 3,000 unexploded bombs around Berlin and 250,000 across the country, waiting to be discovered and, assuming everything goes right, diffused.

Bonus finds: the Viceroy of Ireland’s stash of tiaras and other ceremonial jewels, a prehistoric beaver

Every day, we highlight one newly lost or found object, curiosity or wonder. Discover something unusual or amazing? Tell us about it! Send your finds to sarah.laskow@atlasobscura.com.