Suetonius Divus Claudius 20

He completed some important public works, which, though, not numerous, were very useful. The principal were an aqueduct, which had been begun by Caius; an emissary for the discharge of the waters of the Fucine lake, ¹ and the harbour of Ostia ; although he knew that Augustus had refused to comply with the repeated application of the Marsians for one of these; and that the other had been several times intended by Julius Caesar, but as often abandoned on account of the difficulty of its execution. He brought to the city the cool and plentiful springs of the Claudian water, one of which is called Caeruleus. and the other Curtius and Albudinus, as likewise the river of the New Anio, in a stone canal: and distributed them into many magnificent reservoirs. The canal from the Fucine lake was undertaken as much for the sake of profit, as for the honour of the enterprise; for there were parties who offered to drain it at their own expense, on condition of their having a grant of the land laid dry. With great difficulty he completed a canal three miles in length, partly by cutting through, and partly by tunnelling, a mountain; thirty thousand men being constantly employed in the work for eleven years. ² He formed the harbour at Ostia , by carrying out circular piers on the right and on the left, with a mole protecting, in deep water, the entrance of the port. ³ To secure the foundation of this mole, he sunk the vessel in which the great obelisk ⁴ had been brought from Egypt ; ⁵ and built upon piles a very lofty tower, in imitation of the Pharos at Alexandria , on which lights were burnt to direct mariners in the night.