Thessaloniki: Here comes the metro that brings a millennia-old history back to light

On 2024 November 30, the people of Thessaloniki will celebrate the inauguration of the first metro line in the city’s long history, founded in 315 B.C. by King Cassander of Macedon and named after Thessalonike, the half-sister of Alexander the Great. This grand public work, Greece’s most significant infrastructure project, provides Thessaloniki with a rapid, modern, and sustainable driverless transport system.

Beyond its complex engineering, the new metro line has also offered a unique opportunity to rediscover, protect, and return to the public an invaluable historical and archaeological heritage, hidden for centuries beneath the bustling streets of a city that has become one of the country’s key economic and commercial hubs.

Along the around 10 kilometers of the line, marked by 13 stations that will serve hundreds of thousands of passengers, final preparations are underway to ensure everything is ready for the opening.

A major milestone hinting at this transformation was reached on October 12, when Greek Transport Minister Christos Staikouras attended the opening ceremony of Milan’s M4 line, also built by the Webuild Group, which constructed Thessaloniki’s metro. Thessaloniki’s metro shares a deep connection with both Milan’s M4 and Rome’s Line C, which is currently adding the Venice Station, set to be one of the world’s most impressive “archaeo-stations.”

The engineering challenge was twofold: working within the city’s most populated and congested area, while ensuring preservation of the archaeological finds beneath. Tunnel construction, performed by two TBMs, was accompanied by Thessaloniki‘s most extensive archaeological excavations to date, spanning 30,000 square meters and revealing numerous marble slabs from the famous Roman road, the Decumanus Maximus.

On average, all metro tunnels were built 20 meters deep, ensuring protection for the valuable artifacts closer to the surface. Some stations were redesigned during construction to preserve discoveries in their original location. For instance, Demokratias Station was shifted by 10 meters to better conserve a Byzantine-era wall uncovered during the excavation. This project, therefore, faced a dual challenge: minimizing disruption in Thessaloniki‘s busiest districts while also preserving the archaeological treasures.

Engineers and archaeologists worked side by side, developing innovative solutions to minimize the impact of the digging machines while allowing researchers full access to study and catalog the underground artifacts. Among the findings are not only the Decumanus Maximus, recovered in the area near where the Aghia Sofia station was built, but also ancient Thessaloniki drainage channels, Christian-era buildings, and a Byzantine market with shops and small artifacts.

The urban revitalization of Thessaloniki and the preservation of its historical artifacts are just part of this massive undertaking, which, above all, promises to accelerate the city’s growth. Thessaloniki, already an economic center due to its port (Greece’s second largest after Piraeus) and its many businesses, stands to benefit significantly from the new metro. Built by Webuild in partnership with Hitachi and Aktor, the line will transport around 315,000 passengers daily, with trains arriving every 90 seconds during peak hours. This environmentally friendly addition is expected to reduce CO₂ emissions by 212 tons per day, removing approximately 60,000 vehicles from the roads daily.

The Thessaloniki metro is the latest in a series of major projects by Webuild in Greece, which also include the Athens Metro Line 3, the tramway built for the 2004 Olympic Games, and the Stavros Niarchos Foundation Cultural Center, designed by Renzo Piano and hosting the National Library and Greek National Opera.