The bomb was found during work on a construction site on Wismarer Street close to the Goethe University Frankfurt compound Tuesday, according to a statement by Frankfurt Police.
Police said due to the size of the bomb, extensive evacuation measures were necessary.
The device is a British bomb, specifically a 1.4-ton HC 4000 air mine, the statement said, and is currently under guard by police.
There is no danger to the public, police said, but they will be evacuating the area as a precaution while they defuse the bomb.
The evacuation will take place at 8 a.m. local time on Sunday, authorities said. Further details are expected to be released at a press conference on Thursday.
The Second World War may have ended over 70 years ago but its legacy still lingers in cities across Germany.