THERMAE DIOCLETIANI
the baths erected by Diocletian on the high ground
to the north-east of the Viminal. The dedicatory inscription (CIL
vi. I 130=31242) of which at least four copies were set up runs as follows:
D(omini) n(ostri) Diocletianus et Maximianus invicti seniores Aug(usti),
patres imp(eratorum) et Caes(arum), et d(omini) n(ostri) Constantius
et Maximianus invicti Aug(usti), et Severus et Maximinus nobilissimi
Caesares ... thermas felices Diocletianas, quas Maximianus Aug. rediens
ex Africa sub praesentia maiestatis disposuit ac fieri iussit et Diocletiani
Aug. fratris sui nomine consecravit, coemptis aedeficiis pro tanti operis
magnitudine omni cultu perfectas Romanis suis dedicaverunt. Maximian's return to Rome took place in the autumn of 298; while the
abdication of Diocletian and Maximian in favour of Constantius
(Chlorus) and (Galerius) Maximianus took place on Ist May, 305, and
Constantius died on 25th July, 306. The inscription therefore belongs
to the period between the two latter dates, and the baths took between
seven and eight years to complete. It is noteworthy that the bricks
used belong entirely to the period of Diocletian, no older material having
been employed. The exterior (like that of the thermae of Caracalla
and of the curia) was faced with white stucco in imitation of construction
in blocks of white marble. The date given by Hier. a. Abr. 2318 (302 A.D.),
cf. Chron. 148, is therefore incorrect. The baths are also mentioned
in Not. (Reg. VI) and in Hist. Aug. (xxx. Tyr. 21), where we are told
that the
QUADRIGAE PISONIS (q.v.) were among the buildings removed
to make way for the baths. We may add a monument of an undetermined
period,
1 decorated with sculptures, including a relief representing
the temple of Quirinus (
Mitt. 1904, 23-37), and various private houses,
including that of
CORNELIA L. F. VOLUSI SATURNINI (q.v.); while the
north-eastern portion of the vicus Longus was suppressed, and the Alta
Semita and the Vicus Collis Viminalis connected by a new cross street
(
BC 1880, 132;
1887, 181;
1888, 36; the streets are shown by LF 17
and HF i, ii; cf.
RhM 1894, 383, 388).
The statement in Hist. Aug. Prob. c. 2:
usus autem sum praecipue
libris ex bibliotheca Ulpia, aetate mea thermis Diocletiani, is a pure
invention according to v. Domaszewski (
SHA 1916, 7. A, 9). If it is true
that these thermae could accommodate 3000 people in marble seats,
almost double the number of bathers that found room in those of
Caracalla (Olympiod. ap. Phot. 80, p. 63 a, Bekker, v. p. 521), then,
inasmuch as the area is about the same, the space must have been
more economically used. They are also mentioned by Schol.
Iuv.
xi. 56, and Sidon. ad Consent. 495.
CIL vi. 1131 (the date of which
is uncertain) refers apparently to a restoration, saying '
thermas
Diocletianas a veteribus principibus institutas omn[i cultu ... restituit].'
The destruction of the aqueducts in the Gothic wars naturally rendered
them unusable; but they are mentioned as in the fourth ecclesiastical
region in Regest. Honor. i. a. 625 ap. Deusdedit (iii. c. 138); and the
name in thermis Diocletianis was applied to the church of S. Cyriacus
right through the Middle Ages (HCh 245, 246), while in the Mirabilia (27)
and in Magister Gregorius (
JRS 1919, 52) the building is known as the
Palatium Diocletiani.
The thermae of Diocletian (Ill. 54, a view taken shortly after the
construction of the first railway station) occupied about the same area
as those of Caracalla (a rectangle of about 356 by 316 metres, or about
281 acres) and closely resemble them in plan. The central hall of the
main building, which measured 280 by 160 metres, wrongly known as
the tepidarium until quite recently, is derived, as Rivoira points out,
from that of the thermae of Titus and of Trajan, and is very similar to
that of the baths of Caracalla; while from it is derived the plan of the
Basilica of Constantine. Its excellent preservation is due to its conversion
into the church of S. Maria degli Angeli by Michelangelo; though there
is not sufficient evidence to allow us to attribute to him, instead of to
Vanvitelli, the new apse on the north-east side (cf. Roma iii.
(1925), 349-
356, 395-408). It has an intersecting vault divided into three bays; the
four columns of grey granite on each side do not support the vault,
but are purely ornamental. The four smaller rooms at the angles may
havc served for cold baths, as there is no trace of heating; while
between them, on the minor axis, there was access to the frigidarium
on the north-east and to the circular tepidarium (now the vestibule of
the church) and the rectangular caldarium, which projected south-
westwards, and though extant in the sixteenth century is now
destroyed; see DuP 127.
On the major axis, on the south-west, there was an approach at each
end through two rectangular halls (on each side of which were others) to
the palaestrae, one at each end of the main block on each side of the
frigidarium, a hall containing a huge shallow bathing pool, which was
open to the air; its north wall, elaborately decorated with niches, is
still in great part preserved; see Piranesi, Vedute di Roma, No. 115
Hind, and 111. 53. On each side of the caldarium were the apodyteria
or dressing rooms, and other halls, which served for private baths, etc.,
as well as for conversation, recitations of poets, rhetoricians, etc.,
and completed the rectangular central block.
2 This was surrounded
by a garden, which was enclosed by an outer peribolus. Around this
were small rectangular halls and semicircular exedrae, which were also
used as reading and lecture rooms, gymnasia and lounging rooms.
In the centre of the south-west side was a very large exedra, which
was doubtless provided with seats and served as a theatre (like the
corresponding exedrae in the thermae of Trajan and Caracalla).
The actual enclosure wall was preserved until modern days. The Via
Nazionale was driven through it in 1867, and only the line of its curve is
still shown by the buildings of the Piazza dell' Esedra dei Termini, the
corrupt form in which the name of the thermae still lingers on. At the
west and south angles of the peribolus are two circular halls, one of
which is especially well preserved, owing to its conversion into the church
of S. Bernardo in 1598.
3
The whole of the external brick facing was covered with plaster, in
imitation of construction in blocks of white marble with draughted
joints: this was also done in the thermae of Caracalla, the basilica of
Constantine, etc.
The reservoir by which the baths were supplied was fed by the aqua
Marcia, the volume of which was increased by Diocletian (see p. 27).
It lay outside the peribolus on the south side; and, being in the angle
between the baths and the vicus Collis Viminalis, it was trapezoidal in
shape, 91 metres in length, with an average width of 16 metres. The
last remains of it above ground were not destroyed until 1876 (Falda,
Giardini di Roma, 14; LA 308, 318; BC 1872-3, 230;
1906, 106-107;
Archaeologia li. 502, fig. 12; HJ 382, n. 22;
JRS 1919, 190).
For the excavations and demolitions of the fifteenth and sixteenth
centuries and the condition of the ruins at that period, see
BA 1909,
361-372, 401-405; LS passim (esp. i. 148;
ii. 135-149); DuP 125-
128; HCh 245, 246, 589, 590. The ruins of the caldarium and the
southern angle of the central block were in large measure removed by
Sixtus V.
For the thermae in general, see Sebastianus de Oya,
4 1558 (Brunet,
Manuel iv. 302) ; Paulin, Restauration des Thermes de Diocletien
5 (Paris 1890); D'Esp.
Mon. ii. 162-171 ;
Fr. i. 98, 99; LR 434-437; LS passim;
HJ 377-382;
BA 1911, 347-361 ; Paribeni, Le Terme di Diocleziano ed ii
Museo Nazionale Romano, 9-56;
Toeb. i. 1113; RA 204-210 (superseding
Journal of the Brit. and Am. Arch.
Soc. iv. 353-360); Mem. L. 5. xvii. 533;
RE ii. 2755; ASA 106, 107.