Piraeus of social problems also emerged with the concentration of new populations in the suburbs of the old city, such as Nikaia, Keratsini, Drapetsona and Korydallos. The involvement of Greece in World War II came as a major setback to the city's progress. After the war, the city began its development once more, as damage to the port and the city were repaired and new additions took shape after 1955. Piraeus is now the third largest municipality in Greece; the city proper with its suburbs form the Piraeus urban area, which is incorporated in the Athens urban area, thus making Piraeus
Piraeus-Perama light railway at Methonis street, allowing freight trains to access Keratsini Port. At Keratsini a short branch was constructed leading to one of the jetties. Due to serious damages on infrastructure and rolling stock caused by Allied bombing of Piraeus on 11 January 1944 the line paused service until April 1945. Most of its time the line was exploited with two kind of regular services: one full length service from Piraeus to the Naval Base, running every 15 minutes with two car formation of the rolling stock (line number 4) and in between, 7,5 minutes after, a short service from Piraeus to