Portus

Portus was a large artificial harbour complex of Ancient Rome located at the mouth of the Tiber on the Tyrrhenian Sea. It was established by Claudius and enlarged by Trajan to supplement the nearby port of Ostia.. At its maximum extent the complex covered an area of about 350 hectares and included many horrea and an imperial palace.

Portus was the main port of ancient Rome for more than 500 years and provided a conduit for everything from glass, ceramics, marble and slaves to wild animals caught in Africa and shipped to Rome for spectacles in the Colosseum.

The archaeological remains of Portus are near the modern-day village of Porto within the comune of Fiumicino, Lazio, just southwest of Rome.

Ancient Rome's original port was Ostia located at the mouth of the Tiber on the Tyrrhenian Sea. The Tiber splits into two streams at its mouth, today roughly 1 mile before reaching the sea due to the constant silting from the mouth of the river, with Ostia situated on the larger southern stream but in Roman times the sea was much nearer to Ostia. Emperor Claudius constructed the first harbour on the Portus site, 4 km (2+1⁄2 mi) north of Ostia, enclosing an area of 250 ha (617 acres). According to Cassius Dio:

Claudius excavated a very considerable tract of land, built retaining walls on every side of the excavation, and then let the sea into it. Secondly, in the sea itself he constructed huge moles on both sides of the entrance and thus enclosed a large body of water, in the midst of which he reared an island and placed on it a tower with a beacon light

The foundation of this lighthouse was provided by filling one of the massive obelisk ships, used to transport an obelisk from Egypt to adorn the spina of the Circus of Caligula. The lighthouse was a famous landmark and probably built in imitation of the Pharos at Alexandria. It was depicted in many ancient sculptures, mosaics, coins etc. and its remains could still be seen in the 15th century.

The harbour opened directly to the sea on the northwest and communicated with the Tiber by a channel on the southeast. The goal was to obtain protection from the prevalent southwest wind, to which the river mouth was exposed. Though Claudius, in the inscription which he erected in 46, stated that he had freed the city of Rome from the danger of inundation, his work was only partially successful: in 62 Tacitus speaks of a number of grain ships sinking within the harbour during a violent storm. Nero gave the harbour the name of "Portus Augusti". A canal, later called the Fossa Traiana (today's Fiumicino canal), was built to connect the Harbour of Claudius with the Tiber, allowing barges to travel up towards Rome with cargo transferred from seafaring cargo ships.

It was probably Claudius who constructed the new direct road from Rome to Portus, the Via Portuensis, which was 24 km (15 mi) long. The Via Portuensis ran over the hills as far as the modern Ponte Galeria, and then straight across the plain. An older road, the Via Campana, ran along the foot of the hills, following the right bank of the Tiber. It passed the grove of the Arval Brothers at the sixth mile, to the Campus salinarum romanarum, the saltmarsh on the right bank from which it derived its name.