Greek army experts have defused 314 bombs in an underground storage room at the old Athens airport, which has been closed since 2001.
As the Athens newspaper Kathimerini reported on Friday, citing experts from the landmine clearance battalion (TENX), the bombs dated back to World War II. They were stored 2 metres underground.
"We are only alive by chance," Giannis Konstantatos, mayor of the region, said on Greek radio.
Above and next to the storage area there were airport facilities for eight decades and, after its closure, schools, kindergartens and, during the 2004 Olympic Games in Athens, sports facilities.
According to the mayor, the German Luftwaffe had stored the bombs in the old airport on the coast of Athens during the 1941-44 occupation of Greece and left them behind when they hastily left south-east Europe due to the advance of the Red Army in the Balkans.
"The bombs lay next to our houses for 80 years," he told Kathimerini.
A huge new city district is currently being built on the approximately 620-hectare airport site on the coast of Athens. New hotels and numerous luxury residential complexes are being built.
The work is now being hampered by the danger of more bombs underground, Greek media reported.