Please note that Mommsen uses the AUC chronology (Ab Urbe Condita), i.e. from the founding of the City of Rome. You can use this reference table to have the B.C. dates
From: The History of Rome, by Theodor Mommsen
Translated with the sanction of the author by William Purdie Dickson
At this last spot was situated the double harbour of the city, a work of human hands; the outer or commercial harbour, a longish rectangle with the narrow end turned to the sea, from whose entrance, only 70 feet wide, broad quays stretched along the water on both sides, and the inner circular war-harbour, the Cothon,(14) with the island containing the admiral's house in the middle, which was approached through the outer harbour.
14. That this Phoenician word signifies a basin excavated in a circular shape, is shown both by Diodorus (iii. 44), and by its being employed by the Greeks to denote a "cup." It thus suits only the inner harbour of Carthage, and in that sense it is used by Strabo (xvii. 2, 14, where it is strictly applied to the admiral's island) and Fest. Ep. v. -cothones-, p. 37. Appian (Pun. 127) is not quite accurate in describing the rectangular harbour in front of the Cothon as part of it.
Between the two passed the city wall, which turning eastward from the Byrsa excluded the tongue of land and the outer harbour, but included the war-harbour, so that the entrance to the latter must be conceived as capable of being closed like a gate. Not far from the war-harbour lay the marketplace, which was connected by three narrow streets with the citadel open on the side towards the town.
To the north of, and beyond, the city proper, the pretty considerable space of the modern El Mersa, even at that time occupied in great part by villas and well-watered gardens, and then called Magalia, had a circumvallation of its own joining on to the city wall. On the opposite point of the peninsula, the Jebel-Khawi near the modern village of Ghamart, lay the necropolis. These three--the old city, the suburb, and the necropolis--together filled the whole breadth of the promontory on its side next the gulf, and were only accessible by the two highways leading to Utica and Tunes along that narrow tongue of land, which, although not closed by a wall, yet afforded a most advantageous position for the armies taking their stand under the protection of the capital with the view of protecting it in return.
The difficult task of reducing so well fortified a city was rendered still more difficult by the fact, that the resources of the capital itself and of its territory which still included 800 townships and was mostly under the power of the emigrant party on the one hand, and the numerous tribes of the free or half-free Libyans hostile to Massinissa on the other, enabled the Carthaginians simultaneously with their defence of the city to keep a numerous army in the field-- an army which, from the desperate temper of the emigrants and the serviceableness of the light Numidian cavalry, the besiegers could not afford to disregard.
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Reference address : https://www.ellopos.net/elpenor/rome/4-01-gracchi.asp?pg=52