Authorities in Cologne are carrying out the city’s largest post-war evacuation after three large unexploded American bombs from the Second World War were discovered on Monday.

The operation, affecting around 20,000 residents, was triggered by the discovery of two 1,000kg bombs and one 500kg bomb, prompting a large-scale response from bomb disposal teams.

The massive Cologne WWII bomb evacuation involves clearing a 1,000-meter danger zone encompassing the Old Town and Deutz districts.

Local officials have begun going door to door to ensure that residents, businesses, and institutions are fully evacuated before bomb technicians begin their work.

City officials confirmed that the bombs, left over from Allied bombing campaigns, require a wide exclusion zone due to their size and potential blast impact. The area affected includes Cologne’s UNESCO-listed cathedral, the main city hall, a hospital, nine schools, 58 hotels, and numerous homes and businesses.

Two temporary shelters have been opened to accommodate those displaced by the operation, which is expected to continue through at least Wednesday night.

City center shut down as bomb experts move in

The bomb disposal unit is evaluating whether the unexploded bombs can be safely defused on site.

If not, the alternative would involve a controlled detonation, a far more complex operation requiring the delivery of sand and water to absorb the blast and protect surrounding infrastructure.

Speaking to Sky News, city authorities stressed that defusal remains the preferred option, but safety remains the top priority.

This latest WWII bomb defusal operation in Germany underscores the lasting legacy of wartime bombing campaigns.

Cologne, in particular, was a key target of Allied air raids. On May 30, 1942, it became the first German city to experience a "1,000 bomber raid" by the Royal Air Force, during which 1,400 tons of bombs were dropped in a single night.

It remains unclear from which raid the newly discovered bombs originate, but their presence highlights the enduring risks posed by unexploded ordnance.

History of bomb discoveries in Cologne continues

Cologne has long been a hotspot for unexploded bomb discoveries. Officials estimate that of the 1.5 million bombs dropped on the city during World War II, roughly 20% failed to detonate. In 2024 alone, 31 bombs were uncovered, requiring 17 separate evacuations that affected more than 36,000 people.

These included a 1,000kg bomb and five 500kg bombs, as well as several unexploded grenades.

Authorities are hopeful that if all goes as planned, the current Cologne WWII bomb evacuation will conclude safely by Wednesday evening, allowing residents to return to their homes. Until then, large sections of the city will remain off limits as the delicate work of neutralizing the wartime explosives continues.