The 500-kg British bomb was discovered during building work this week, more than seven decades after the end of World War Two.
Some 10,000 people - including residents, hospital patients and office workers - were evacuated from 9 a.m. from buildings within an 800 metre radius of the bomb while experts performed the delicate operation.
Police posted a video on Twitter showing officers walking up the stairs in an apartment building with the caption: "We're not bringing room service or breakfast in bed but a personal wake-up call."
Long-distance and local train transport at the central station was disrupted for several hours but police said on Twitter that the station had now re-opened. Bus and tram services also restarted.
Some roads were closed but were due to gradually reopen.
Germany still discovers more than 2,000 tonnes of live bombs and munitions every year.
Last year some 60,000 people were evacuated from their homes in Frankfurt after a massive bomb dropped by Britain's Royal Air Force was unearthed.
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