[1][2][3] In his book Ab urbe condita, Livy mentions the presence of "the docks at Rome".
[4] These are paired with consular names that suggest dates in the middle of the fourth century BCE, the earliest mentions we have.
They were clearly important, as indicated by an expansion project in the second century BCE that attracted the talent of the Greek architect Hermodorus of Salamis, then actively involved in several high-profile buildings.
[3] The exact location is unknown but the consensus view south of the Campus Martius is supported a passage in Plutarch mentioning the younger Cato returning from Cyprus in triumph.
The text is helpfully descriptive: he is described as sailing through Rome on the Tiber, ignoring cheering crowds lining the river and not stopping before reaching "the dockyard".