Pisa’s origins are unknown. The city lies at the junction of two rivers, Arno and Auser (now disappeared) in the Ligurian Sea forming a laguna area. The Pelasgi, the Greeks, the Etruscans and the Ligurians have variously been proposed as founders of the city. Archeological remains from the 5th century BC confirm the existence of a city at the sea, trading with Greeks and Gauls.
The presence of an Etruscan necropolis was discovered during excavations in the Arena Garibaldi in 1991. Also ancient Roman authors referred to Pisa as a very old and ancient city dating back 1300 years before the birth of Christ.
The maritime role of Pisa should have been already prominent if the ancient authorities ascribed to it the invention of the rostrum: it took advantage of being the only port along the coast, from Genoa, then a small village, to Ostia. Pisa served as a base for Roman naval expeditions against Ligurians, Gauls and Carthaginians. In 180 BC it became a Roman colony under Roman law, as Portus Pisanus. In 89 BC, Portus Pisanus became a municipium. Emperor Augustus fortified the colony into an important port and changed the name in Colonia Iulia obsequens. From 313 it became the seat of a bishopric.
