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
Whether, or to what extent, a national Italian architecture arose
o ut of these beginnings can scarcely be determined, for in this
field Greek influence, even in the earliest times, had a very
powerful effect and almost wholly overgrew such national attempts
as possibly had preceded it. The very oldest Italian architecture
with which we are acquainted is not much less under the influence
of that of Greece than the architecture of the Augustan age.
The
primitive tombs of Caere and Alsium, and probably the oldest one
also of those recently discovered at Praeneste, have been, exactly
like the θησαυροί of Orchomenos and Mycenae, roofed over with
courses of stone placed one above another, gradually overlapping,
and closed by a large stone cover. A very ancient building at
the city wall of Tusculum was roofed in the same way, and so was
originally the well-house (-tullianum-) at the foot of the Capitol,
till the top was pulled down to make room for another building.
The gates constructed on the same system are entirely similar in
Arpinum and in Mycenae.