The all-day effort on Sunday took longer than planned, but officials expressed relief that residents would start returning home before sundown and that the operation would not disrupt business on Monday (local time).
The work by bomb technicians started later than planned as some people refused to leave the evacuation area despite fire chiefs warning an uncontrolled explosion would be big enough to flatten a city block. Police said they took stragglers into custody to secure the area.
More than 1,000 emergency service workers helped to clear the area and a steady flow of people filed into a temporary shelter at Frankfurt’s trade fair site, enjoying bananas and beverages on offer. Others sat in cafes on the edge of the evacuation zone.
Police set up cordons around the evacuation area, which covered a radius of 1.5 km.
Premature babies and intensive care patients had to be evacuated along with everyone else from two hospitals and rescue workers helped about 500 elderly people leave residences and care homes.
Bomb disposal experts reportedly used a special system to unscrew the fuses attached to the HC 4,000 bomb from a safe distance. If that had failed, a water jet would have been used to cut the fuses.
Live bomb discoveries not uncommon in Germany
The bomb was dropped by Britain’s Royal Air Force during the1939-45 war, city officials said. British and American warplanes pummelled Germany with 1.5 million tonnes of bombs that killed 600,000 people.
Officials estimate 15 per cent of the bombs failed to explode, some burrowing six metres deep.
More than 2,000 tonnes of live bombs and munitions are found each year in Germany, even under buildings. In July, a kindergarten was evacuated after teachers discovered an unexploded World War II bomb on a shelf among some toys.
Three police explosives experts in Goettingen were killed in 2010 while preparing to defuse a 450 kg bomb.
In Frankfurt, roads and transport systems, including parts of the underground, were to remain closed during the work and for at least two hours after the bomb is defused, to allow patients to be transported back to hospitals.
Air traffic from Frankfurt airport could also be affected and small private planes, helicopters and drones were banned from the evacuation zone.
Museums were offering residents free entry on Sunday, and many hotels offered discounts.