Later it became one of the main Roman settlements in Liguria. It was located in a strategic position along the via Aurelia, and connected to a port which in the early centuries of the Christian Era was filled with debris, losing importance and bringing about the decadence of the town.
Still flourishing in 416 AD when Rutilius Namatianus described its white walls and shining marbles, a bishopric seat in the 5th century, was finally occupied and almost destroyed by the Lombards under king Rotari, its inhabitants dispersed and on the place only a small village remained.
Archeological excavations, performed along the left bank of the Magra river brought back to light the rectangular perimeter of the colony, with sides 560 x 438 metres long, a theatre in the north-eastern corner, a huge temple dedicated to the Luna goddess, in the center of the town the Forum, crossed by the decumanus maximus, a part of the via Aurelia.
Other important elements founded in the excavations were two rich mansions, the House of Mosaics and the House of Frescoes, both dating back to the 3rd century AD. A huge amphitheater, still in very good conditions, was outside the walls, and could contain 7,000 people; the amphitheater is still used today in the summer months. Near the amphitheater there are remains of a Mausoleum, and an early Christian Church, where a Museum was established to preserve many of the items found during the excavations, such as bronze statues, jewels, marble portraits, and a great many fragments of constructions and mosaics.