creation of a metro system for Thessaloniki goes back as far as 1918, when Thomas Hayton Mawson and Ernest Hébrard proposed the creation of a Thessaloniki Metropolitan Railway. In 1968, a circular metro line was proposed, and in 1987 the first serious proposal was presented and construction briefly started in 1988, before stalling and finally being abandoned due to lack of funding. Both the 1918 and 1988 proposals ran almost the identical route to the current Line 1. Construction on Thessaloniki's current metro began in 2006 and is classified as a megaproject: it has a budget of €1.57 billion ($ billion). Line 1 and Line 2 are currently under construction and will enter service, in phases, between 2023 and 2024. Line 1 is long and stops at 13 stations, while Line 2 is long and stops at a further five stations, while also calling at 11 of the Line 1 stations. Important archaeological discoveries have been made during construction, and some of the system's stations will house archaeological exhibitions. One stop, , will house the only open archaeological site within a metro station anywhere in the world. Line 2 is to be expanded further, with a loop extension to the western suburbs of the city, towards Evosmos and Stavroupoli, and one overground extension towards the Airport. The western extension is more high-priority than the airport one, as the airport will be served by a 10-minute shuttle bus to the terminus of Line 2, . Once it opens in 2023, it is expected that 320,000 people will use the metro every day, or 116 million people every year. Commuter/suburban rail (Proastiakos) Commuter rail services have recently been established between Thessaloniki and the city of Larissa (the service is known in Greek as the "Proastiakos", meaning "Suburban Railway"). The service is operated using Siemens Desiro EMU trains on a modernised electrified double track and stops at 11 refurbished stations, covering the journey in 1 hour and 33 minutes. Furthermore, an additional line has also been established, although with the use of regional trains, between Thessaloniki and the city of Edessa. Thessaloniki Airport "Makedonia" International and domestic air traffic to and from the city is served by Thessaloniki Airport "Makedonia". The short length of the airport's two runways means that it does not currently support intercontinental flights, although a major extension – lengthening one of its runways into the Thermaic Gulf – is