In 42 CE the Emperor Claudius began the construction of a large seaport (Port of Claudius), located 3 km north of the mouth of the Tiber, and completed in 64 CE, under Nero’s principate.
The massive infrastructure ensured a quiet basin in which could be safely carried out the discharge of goods from the large trade vessels arriving from across the Mediterranean as well as their transhipment onto river boats (naves caudicariae) suitable for sailing up the Tiber as far as Rome.
The port basin, spanning more than 200 hectares, was excavated in the dryland partially enclosed on the seaward side by two curved piers converging towards the entrance. There, on an artificial island, stood a gigantic lighthouse, similar to the famous Lighthouse of Alexandria of Egypt, which indicated to seafarers the entrance of the basin. Also, at least two artificial canals ensured the connection between the sea, the Port of Claudius and the Tiber.
The foundations of the right-hand side (or northern) pier are still visible behind the Museum of Ships for an extent of about one kilometre.
On the quay that bordered the dock on the landward side are still preserved some of the functional structures relevant to the port: the so-called Captaincy, a cistern and some thermal buildings constructed, though, in a later period (2nd c. CE) than Claudius’s structure.
The scant security and the progressive silting to which the port was prone, drove the emperor Trajan to build, just 40 years later (between 100 and 112 CE), a new more inward basin, the Port of Trajan. The Port of Claudius, continued, however, to be used as a roadstead.