flowed quite through the city, and its mouth formed an excellent port
where once, as Dion reports [this passage of Dion Cassius is lost], a
fleet of 250 ships could be stationed in all security.... The city has
three names with which she glorifies herself and she is divided into
three parts to which they correspond; the first is Ravenna, the last
Classis, that in the midst is Caesarea between Ravenna and the sea.
Built on a sandy soil this quarter is easily approached and is
commodiously situated for trade and transport."

We thus have a picture of Ravenna as a triune city, consisting of
Ravenna proper, the port Classis, and the long suburb between them,
Caesarea, connected by a great causeway and everywhere watered by
canals, the greatest of which was the Fossa Augusta by which a part of
the waters of the Po were carried to Ravenna and thence to Classis and
the sea; a city very much, we may suppose, what we know Venice to be,
if we think of her in connection with the Riva, the great suburb of
the Marina, and the Porto di Lido. At Classis we must understand there
was room for a fleet of two hundred and fifty ships and accommodation
for arsenals, magazines, barracks, and so forth, while there is one
other thing we know of this port, and that from Pliny,[1] who tells us
that it had a Pharos like the famous one of Alexandria. "There is
another building (says he) that is highly celebrated, the tower that
was built by a king of Egypt on the island of Pharos at the entrance
to the harbour of Alexandria.... At present there are similar fires
lighted up in numerous places, Ostia and Ravenna for example. The only
danger is that when these fires are thus kept burning without
intermission they may be mistaken for stars."

[Footnote 1: Pliny xxx. vi. 18]