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
The Palatine City
The town, which in the course of centuries grew up as Rome, in its original form embraced according to trustworthy testimony only the Palatine, or "square Rome" (-Roma quadrata-), as it was called in later times from the irregularly quadrangular form of the Palatine hill. The gates and walls that enclosed this original city remained visible down to the period of the empire: the sites of two of the former, the Porta Romana near S. Giorgio in Velabro, and the Porta Mugionis at the Arch of Titus, are still known to us, and the Palatine ring-wall is described by Tacitus from his own observation at least on the sides looking towards the Aventine and Caelian. Many traces indicate that this was the centre and original seat of the urban settlement.
On the Palatine was to be found the sacred symbol of that settlement, the "outfit-vault" (-mundus-) as it was called, in which the first settlers deposited a sufficiency of everything necessary for a household and added a clod of their dear native earth. There, too, was situated the building in which all the curies assembled for religious and other purposes, each at its own hearth (-curiae veteres-). There stood the meetinghouse of the "Leapers" (-curia Saliorum-) in which also the sacred shields of Mars were preserved, the sanctuary of the "Wolves" (-Lupercal-), and the dwelling of the priest of Jupiter. On and near this hill the legend of the founding of the city placed the scenes of its leading incidents, and the straw-covered house of Romulus, the shepherd's hut of his foster-father Faustulus, the sacred fig-tree towards which the cradle with the twins had floated, the cornelian cherry-tree that sprang from the shaft of the spear which the founder of the city had hurled from the Aventine over the valley of the Circus into this enclosure, and other such sacred relics were pointed out to the believer.
Temples in the proper sense of the term were still at this time unknown, and accordingly the Palatine has nothing of that sort to show belonging to the primitive age. The public assemblies of the community were early transferred to another locality, so that their original site is unknown; only it may be conjectured that the free space round the -mundus-, afterwards called the -area Apollinis-, was the primitive place of assembly for the burgesses and the senate, and the stage erected over the -mundus- itself the primitive seat of justice of the Roman community.
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Reference address : https://www.ellopos.net/elpenor/rome/1-04-beginnings-rome.asp?pg=10