(historical) A large artificial harbour of Ancient Rome, situated on the north bank of the mouth of the River Tiber, established and enlarged (respectively) by the Emperors Claudius (10 BC–AD 54) and Trajan (AD 53–117), and connected to the Pons Aemilius of Rome by the Via Portuensis.

(historical, nautical, military) A port on the Gulf of Naples, Mediterranean in Baiae, Italia, Roman Empire, the primary naval base of the Western Empire