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.

Tunneling followed ancient commercial routes through the center of the port city that 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.