From the time of Servius to Aurelian the city, though much enlarged,
had no new wall, though the boundaries had been extended. To continue
our last quotation from Dionysius, who died 7 B.C., this is evident.
"But if any one is desirous to measure the circumference of it by the
wall--which, though hard to be discovered, by reason of the buildings
that surround it in many places, yet preserves in several parts of it
some traces of the ancient structure--and to compare it with the
circumference of the city of Athens, the circuit of Rome will not
appear much greater than that of the other" (Dionysius, iv. 13).
The Pomœrium, or city bounds, was enlarged, as we know, by several
emperors, some of their _cippi_, or boundary-stones, being still _in
situ_; but there was no wall. Where the roads crossed the line of the
Pomœrium, gates were built, between which there were no walls. The
Romans considered the rivers Tigris, Euphrates, and Danube, the desert
and the ocean, as the walls of Rome.
"When he [Aurelian] saw that it might happen what had occurred under
Gallienus, having obtained the concurrence of the senate, he extended
the walls of the city of Rome" (Vopiscus, in "Aur.," 21).
"Thus also Rome was surrounded by walls which it _had not before_, and
the wall begun by Aurelian was finished by Probus" (Zosimus, i. 49).
Other quotations might be given to show that Aurelian surrounded the
Rome of the empire with walls which it had not before his time. He
incorporated with his wall everything that stood in his way,--tombs,
aqueducts, palaces, camps, and amphitheatre. It was commenced and
finished in nine years, and had twenty-two gates, nineteen of which
still remain.
These present walls have been in part rebuilt, repaired, and
strengthened at different intervals, as occasion might require, from
the time of Honorius, who improved and added to the existing gates, to
that of Totila, who "resolved to raze Rome to the ground. So, of the
circuit of the walls he threw down as much in different places as
would amount to about a third part of the whole" (Procopius, "Bello
Gothico," iii. 22).
Belisarius "made hasty repairs," after which the Popes stepped in and
took up the tale, and put up inscriptions, so that there should be no
mistake about it. Leo IV. built the walls of the Leonine city, to
protect it from the Saracens, besides repairing the Aurelian walls.
The Leonine walls can still be traced, the ruins standing boldly out
in the landscape at the back of the Vatican.
The present wall on the Trastevere side was built by Innocent X. and
Urban VIII. The complete circuit of the present walls is between
twelve and thirteen miles; they contain twenty gates, ancient and
modern, nine of which are closed.
Whilst the Romans considered the defences of the city to be the
Tigris, Euphrates, Danube, desert, and ocean, their power was at its
zenith; but when for the defence of their capital it was necessary to
surround it with a wall, "the decline and fall of the Roman empire"
had already begun.