The city of Cologne in Germany has successfully completed the evacuation of 20,500 people, marking its largest evacuation since World War II, after officials safely defused three large unexploded bombs.

The bombs, which were American-made and included two weighing 20 tonnes and another weighing 10 tonnes, were discovered in a shipyard on Monday. This prompted the establishment of a significant “danger zone,” leading to early closures on Wednesday.

The evacuation affected various facilities, including a hospital, two retirement centers, and the city’s second-largest train station. Additionally, schools, churches, museums, and two prominent cultural venues—the Musical Dome theatre and the Philharmonic Hall—were located within the evacuation perimeter.

Allied nations conducted 262 air raids of Cologne during World War II, killing approximately 20,000 residents and leaving the city in ruins.

Nearly all of the buildings in the Old Town were destroyed, as were 91 of the city’s 150 churches.

A massive reconstruction effort took place after the war, with the Old Town rebuilt and major landmarks restored.

But small evacuations still take place on a regular basis when unexploded ordnances are found. About 10,000 residents had to leave their homes last October when another American bomb was found, and last December, 3000 people were asked to evacuate.