German authorities in Hanover are evacuating 50,000 residents, or about 10 percent of the city, so experts can safely diffuse five unexploded World War II bombs. The evacuation will begin Sunday, and is expected to be the second largest of its kind in Germany.

This evacuation has been planned for some time, and thousands of people from from nearby cities have come to assist. The government has even scheduled events like museum tours and move viewings to keep residents occupied while they’re a safe distance away from the city.

The bombs are leftover from an Allied forces mission in October 1943 that dropped more than 250,000 bombs in all. Seventy years later and unexploded ordnance from World War II is still a major problem throughout much of the country, especially because as bombs deteriorate they become more dangerous.

The largest bomb-related evacuation came on Christmas day last year, in Augsburg, when about 54,000 people were evacuated after a bomb was found at a construction site. In 2015, 20,000 people in Cologne were also evacuated because of a bomb. In Gottingen in 2010 a bomb exploded and killed three members of the bomb squad attempting to defuse it, and seriously injured two others.

This weekend, trains were rerouted, and others would not stop in Hanover. Hundreds of ambulances were brought into the city to help people leave the area. Within the evacuation zone was a tire plant, seven elderly homes, and a hospital. Residents are expected to be able to return home later in the evening.