Parker, John Henry: The archaeology of Rome (1,2): Illustrations to I. The primitive fortifications. II. The walls and gates of Rome. III. The historical constructions of walls (Oxford [u.a.], 1874)

Primitive Fortifications—Plans and Diagrams.

Plate II.
Roma Primitiva. The object of this Plate is to give a more
clear idea of the original City of Rome, both of the first and second
period. The first City consisted of the Palatine Hill only, of which
the northern part was more strongly fortified than the rest. This
strongest part, or citadel, was an oblong space on the side next the
Hill of Saturn, of which the Sabines were then in possession, and
were for a time at war with the Romans. This space, called Roma
Quadraia, was the arx, citadel, or keep of the Palatine City. It may
have been called Qiiadrata either from its oblong form, or because
it was surrounded by walls built of large oblong blocks of tufa, of
the construction called by Vitruvius Of its quadratum. It had a triple
line of defence round it at different levels, as was usual for the arx.
Remains of the wall against the upper cliff are now visible on three
sides. This wall is distinguished on the plan by a solid red line
where it is now visible, and by a dotted red line where it has been
destroyed, but must have gone. On the south, the west, and the
north, parts of the wall remain against the cliff; on the south side is
the great foss across the middle of the hill, called by some a natural
valley, or intermontium; it was probably partly natural, but certainly
only in part, with the cliffs supported by walls on both sides of the
great foss. The Porta Mugionis is near the east end of this foss,
the approach to it protected by the cliffs on both sides spreading
out in a gorge as usual. The second City consisted of the two hills,
the Palatine and the Hill of Saturn inclosed in one wall, which is
also marked by a red line, solid where it remains, and in dots only
where it must have passed. It must have included the Velia at the
east end, to protect the approach to the principal gate, and have
gone to the Tiber on the south-west in order to keep open that
highway for provisions. The tufa wall of the second period against
the bank of the Tiber, called the Pulchrum Littus, must have formed
part of this line of defence, and the small river Almo may also
have formed a wet ditch for a certain distance. The other streams
and marshes in the valleys added greatly to the strength of the
Palatine fortress, before they were collected in the great drain,
called Cloaca Maxima.