Greece’s second-largest city, Thessaloniki, is getting a brand new subway system that will showcase archaeological discoveries made during construction that held up the project for decades.

The 9.6-kilometer (5.9-mile) inaugural line will officially open on Nov. 30, using driverless trains and platform screen doors. Construction began in earnest in 2003, and a treasure trove of antiquities was unearthed in a vast excavation beneath the densely populated city of a million residents.

"This project offers a remarkable blend of the ancient and modern, integrating archaeological heritage with metro infrastructure," Christos Staikouras, the transport and infrastructure minister, told reporters Friday on a media tour of the subway.

Tunneling followed ancient commercial routes through the center of the port city, which has been continuously inhabited since ancient times. It exposed a Roman-era thoroughfare, ancient Greek burial sites, water and drainage systems, mosaics and inscriptions and tens of thousands of artifacts spanning centuries, also through Byzantine and Ottoman rule.

The tunnels had to be bored at a greater depth than originally planned, adding cost and delays to preserve the ancient discoveries.

Key pieces of what was found have been displayed along the underground network of 13 stations, including a section of the marble-paved Roman thoroughfare at the central Venizelou Station.

"The project faced substantial delays and many challenges, including over 300,000 archaeological finds, many of which are now showcased at various stations along the main line," Staikouras said.

The Thessaloniki metro was first conceived more than a century ago, and its completion has been greeted with quiet amazement by residents who have used the metro project for years as a punchline for bureaucratic delays and undelivered promises.

Government officials said the cost of the metro so far has reached 3 billion euros ($3.1 billion) for the completed first line of the subway system and most of a second line, which is currently under construction and due to be delivered in a year.

The construction consortium was made up of Greece’s Aktor, Italy’s Webuild, and Japan’s Hitachi Rail.