"it would be a tragedy to jeopardise [Greece's reputation for monument preservation] by squandering the treasure of the Thessaloniki material and data through an unnecessarily hasty construction project", arguing that the previous decision to leave the discoveries in-situ was preferable. Line 2 (Kalamaria Extension) The Kalamaria Extension () extends the metro system to Kalamaria, the second-largest municipality in the Thessaloniki urban area and the 18th-most-populous in Greece. Similar in construction to Line 1, it has two parallel single-track tunnels on a route between and and adds five stations to the network. Construction on the project began in 2013, with an budget of €518 million ($ million). By 31 July 2018, the extension was 60 percent completed. Although construction began seven years after Line 1, it is expected to fully enter service in November 2023. This is due to the lack of major archaeological works, enabling the project to proceed without delays. The latest Attiko Metro financial statement puts the extension's costs at €568 million ($ million). An April 2019 update raised the estimated cost to €640 million ($ million). The line is made up of 16 stations, 11 of which are also stations served by Line 1. After confusion about the extension's place in the system, Attiko Metro clarified in August 2018 that it would be a separate line running between and without the need to change trains at . The extension of Line 2 to Makedonia Airport went to tender in March 2019 with an initial budget of €254,150 ($ thousand) for topographical works in order to enable more detailed planning of the line. Future extensions The system is planned to be extended further, with a four-station eastern extension to Line 2 (towards Macedonia International Airport) and an eight-station loop in the west. The latter is a priority for Attiko Metro to connect the city's western working class suburbs with the city centre, since the airport will be serviced by a 10-minute shuttle-bus trip to (the eastern terminus of Line 2). The two western extensions were originally planned as separate lines, but were merged into a single circular line of in length in 2018. Work on the western extensions was scheduled to enter the tendering process in the autumn 2018. Attiko Metro confirmed in early 2019 that preliminary works for the western loop will begin in 2019. According to Attiko Metro, the double-track airport extension will be a mixture