The €550m project included the construction of new stations at Ilioupoli, Alimos, Argyroupoli, and Elliniko. At Alimos and Argyroupoli, artefacts uncovered during the construction of the line are on permanent display.
Construction was completed as long ago as early 2011, but the official opening has been delayed by an investigation into allegations of corruption against Siemens, which supplied the signalling systems for lines 2 and 3.
Athens Metro initially planned to build this section of the line on viaduct along the central reservation of Vouliagmenis Avenue, but following concerns over noise, a new tender was issued for a more costly underground alignment. The contract was finally awarded in March 2006.
The extension is expected to carry around 83,000 passengers per day and will reduce the number of car journeys on Vouliagmenis Avenue by around 13,000 per day.
Athens Metro expects to issue a tender before the end of the year for the construction of a light rail extension to an interchange with Line 2 at Argyroupoli, which will provide better access to the metro from the southern suburbs of the city.