The Athens Metro ranks as one of the largest public works projects in the history of Greece and one of the largest currently underway in Europe. When fully operational, the two lines will carry 140 million passengers a year or 450 000 daily. The existing Athens-Pireas Electric Railway line carries approximately 110 million passengers annually or 350 000 per day.

The day interval between trains will be 3 minutes during rush hours and 5 to 10 minutes in non-rush hours. The project will produce 2,5 million cubic meters of excavated rock and soil and utilize 700 000 cubic meters of concrete and 60 000 tons of structural and reinforcing steel. Two tunnels boring machines designed in Japan and manufactured in France will handle approximately 90% of the tunneling of the project, which will be conducted at an average depth of 20 meters. 69 000 square meters of archaeological investigations represent the largest single effort ever undertaken within Athens.

In 1961 there were 39 000 automobiles in Athens, while today there are 1,4 million. Over the last 20 years the percentage of Athenians using public transportation declined from 70% to 35%. The new Metro, however, is expected to reverse this trend. By car in rush hour it now takes 35 minutes to drive from Pentagono to Syntagma; with the Metro it will take 9 minutes. A similar trip from Dafni to Omonia will be reduced from 35 to 10 minutes.