Officials ordered residents to evacuate homes within a 1.5-kilometre (nearly a mile) radius of the site in Germany's financial capital.
Explosive experts defused a massive World War Two bomb after tens of thousands of people evacuated their homes in Frankfurt, Germany.
The operation in central Frankfurt to get residents to safety was the biggest evacuation of its kind in post-war Germany, the city's security chief said.
More than 70 years after the end of the war, unexploded bombs are regularly found buried in Germany, legacies of the intense bombing campaigns by the Allied forces against Nazi Germany.
"We are still working on the modalities of the evacuation plan", a spokeswoman for Frankfurt police said on Wednesday.
Helicopters with heat seeking devices scoured the area before the bomb experts began their work. More than a thousand emergency service workers helped to clear the area and people filed into a temporary shelter at Frankfurt's trade fair site.
Even premature babies and intensive care patients had to evacuate along with the remaining patients from two hospitals and around 500 elderly residents of a care home.
Bomb disposal experts used a special system to try and unscrew the fuses attached to the HC 4,000 bomb from a safe distance.