connected Placentia through Mutina with the Via Flaminia at Rimini.
This was the work of the Consul Aemilius Lepidus in 187 B.C. and the
road still bears his name.

It is obvious then that the command of the way from Italy into
Cisalpine Gaul, or _vice versa_, lay in the hands of Rimini, and it is
significant that the political boundary between them was here marked
by a little river, the Rubicon, a few miles to the north of that city.
The command which Rimini thus held was purely political; it passed
from her to Ravenna automatically whenever that entry was threatened.
Why?

The answer is very simple: because Rimini could not easily be
defended, while Ravenna was impregnable.

Ravenna stood from fifteen to eighteen miles north and east of the
Aemilian Way and some thirty-one miles north and a little west of
Rimini. Its extraordinary situation was almost unique in antiquity and
is only matched by one city of later times--Venice. It was built as
Venice is literally upon the waters. Strabo thus describes it:
"Situated in the marshes is the great Ravenna, built entirely on
piles, and traversed by canals which you cross by bridges or
ferry-boats. At the full tides it is washed by a considerable quantity
of sea water, as well as by the river, and thus the sewage is carried
off and the air purified; in fact, the district is considered so
salubrious that the (Roman) governors have selected it as a spot in
which to bring up and exercise the gladiators. It is a remarkable
peculiarity of this place that, though situated in the midst of a
marsh, the air is perfectly innocuous."[1]