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
Chronicle certainly nowhere presents truth without fiction, and it
would be very foolish to quarrel with Naevius and Pictor because
they have not acted otherwise than Hecataeus and Saxo Grammaticus;
but the later attempts to build houses out of such castles in the
air put even the most tried patience to a severe test No blank in
tradition presents so wide a chasm, but that this system of smooth
and downright invention will fill it up with playful facility.
The eclipses of the sun, the numbers of the census, family-registers,
triumphs, are without hesitation carried back from the current year
up to the year One; it stands duly recorded, in what year, month,
and day king Romulus went up to heaven, and how king Servius
Tullius triumphed over the Etruscans first on the 25th November
183, and again on the 25th May 187, In entire harmony with such
details accordingly the vessel in which Aeneas had voyaged from
Ilion to Latium was shown in the Roman docks, and even the
identical sow, which had served as a guide to Aeneas, was preserved
well pickled in the Roman temple of Vesta.