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
Situation of Carthage
Carthage was rendered very strong both by the nature of its situation(8) and by the art of its inhabitants, who had very often to depend on the protection of its walls. Into the broad gulf of Tunis, which is bounded on the west by Cape Farina and on the east by Cape Bon, there projects in a direction from west to east a promontory, which is encompassed on three sides by the sea and is connected with the mainland only towards the west.
8. The line of the coast has been in the course of centuries so much changed that the former local relations are but imperfectly recognizable on the ancient site. The name of the city is preserved by Cape Cartagena--also called from the saint's tomb found there Ras Sidi bu Said--the eastern headland of the peninsula, projecting into the gulf with its highest point rising to 393 feet above the level of the sea.
This promontory, at its narrowest part only about two miles broad and on the whole flat, again expands towards the gulf, and terminates there in the two heights of Jebel-Khawi and Sidi bu Said, between which extends the plain of El Mersa. On its southern portion which ends in the height of Sidi bu Said lay the city of Carthage. The pretty steep declivity of that height towards the gulf and its numerous rocks and shallows gave natural strength to the side of the city next to the gulf, and a simple circumvallation was sufficient there.
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Reference address : https://www.ellopos.net/elpenor/rome/4-01-gracchi.asp?pg=48