space, 430 yds. long by 380 yds. wide, and was originally enclosed
by a battlemented wall, 12 ft. in height, against which vaulted
chambers were built on the inside. Aurelian included the camp in
his fortifications (p. 176) and doubled the height of the wall. Con-
stantine, who disbanded the Preetorian guards, destroyed their camp
so far as it did not form part of the town-wall. The Castro, which
now contains modern barracks, is again devoted to military pur-
poses and accessible only by special permission.
Two of the ancient gates (on the N. side, nearly opposite the 'Officina
Elettrica', and on the E. side), both dating from the reign of Tiberius,
are still extant and are good examples of Roman brickwork. The wall
on the S. side was hastily repaired in the early middle ages with blocks
of stone from ancient buildings.
To the E. is the large Policlinico (Pl. I, 32, 33), or clinical hos-
pital, a handsome building designed by G. Podesti and completed
in 1896, but not opened until 1905.
In the town-wall at the S.W. angle of the Castro Pretorio is a
Gateway, of the time of Aurelian, the ancient name of which is
unknown. It seems to have been built up in the reign of Honorius.
— Hence to the Porta San Lorenzo (p. 210), 12 minutes.
c. Piazza delle Terme. Via Nazionale. The Quirinal.
On the S.E. side of the Piazza Delle, Terme and the adjoining
Piazza del Cinquecento (Pl. I, 27) is the Railway Station, con-
structed in 1872. Opposite the arrival-platform begins the wide
Via Cavour, leading to the Piazza dell' Esquilino and the Forum
(see p. 214). — In front of the main façade of the station, which
faces the Thermæ of Diocletian, is a Monument to the 500 Italian
soldiers who were surprised and slain at Dogáli by the Abyssinians
in 1886. A small obelisk from the temple of Isis (p. 234), found
in 1882, has been incorporated in this monument. — To the E. of
the station stands the most important extant fragment of the For-
tifications of Servius (p. xxx), which consisted here of a rampart
about 100 ft. in breadth and 50 ft. in height. The extant wall, about
40 ft. high, was originally banked up with earth on the inner side.
Tramways and Omnibuses, see Appendix.
The Thermæ of Diocletian (Pl. I, 27), which give name to
the piazza, were the most extensive thermæ in Rome, and were com-
pleted by Diocletian and his co-regent Maximian in A.D. 305-6.
The principal building was enclosed by a peribolos, the outline of
the round central portion ('exedra') of which is preserved by the
modern houses at the beginning of the Via Nazionale (p. 199). The
corners were occupied by circular domed structures, one of which
is now the church of San Bernardo (p. 188), and another is built
into a girls' school on the Via Viminale. The circumference of the
baths is said to have been about 2000 yds., or half as much again