Three inscriptions on the Porta Maggiore in Rome: Claudius (in 52 ad) stated that he - at his own expense - brought water to Rome. Vespasian (in 71 ad) and Titus (81 ad), both at own expenses too, made the necessary repairs as they proudly mention. Above the Porta Tiburtina in Rome Augustus (4 bc), Caracalla (212 ad) and Titus (79 ad) made mention the repairs they made on the Aqua Marcia. Not only texts were depicted in inscriptions. CIL6.1261 gave an idea about water distribution in a rural area around Rome by means of sluices. Some people received water on certain hours only. Note the two rectangles, probably storage basins.
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Inscriptions

Inscriptions are an important source of information regarding the aqueducts of Rome. In lieu of examining the original inscriptions, the Corpus Inscriptionum Latinarum 'CIL' is used. The most important inscriptions related to Rome are in Volume 6, especially CIL 6.1243 - CIL 6.1268.

There are some limitations in using epigraphic evidence. One such limitation is that none of the inscriptions are earlier than the Augustan age (Sandys, 1927:129). Another is that inscriptions where not always intended to record fact; ancient politicians and emperors were well understood the value of propaganda.

We will now examine some of the important extant inscriptions.

Porta Praenestina / Porta Maggiore

Above the rough stones of the arches of the Porta Praenestina, or Porta Maggiore, the smooth walls of the channels carries three inscriptions. The top inscription is bordered above and below by stone slabs that project from the roof and floor of the Anio Novus channel (Aicher, 1995:54). The inscription reads (CIL 6.1256):
TI. CLAUDIUS DRUSI F. CAISAR AUGUSTUS GERMANICUS PONTIF. MAXIM.,
TRIBUNICIA POTESTATE XII, COS. V, IMPERATOR XXVII, PATER PATRIAE,
AQUAS CLAUDIAM EX FONTIBUS, QUI VOCABANTUR CAERULEUS ET CURTIUS A MILLIARIO XXXXV,
ITEM ANIENEM NOVAM A MILLIARIO LXII SUA IMPENSA IN URBEM PERDUCENDAS CURAVIT.
This is a commemoration of the construction of the Claudia and Anio Novus, in 52 AD, by the emperor Claudius, 'at his own expense'. It states the sources for both, the former at the 45th milestone and the latter at the 62nd milestone.
The second inscription is framed by horizontal mouldings that extend the floor and roof of the Claudia conduit. It reads (CIL 6.1257):
IMP. CAESAR VESPASIANUS AUGUST. PONTIF. MAX., TRIB. POT. II, IMP. VI, COS. III DESIG. IIII, P.P.,
AQUAS CURTIAM ET CAERULEAM PERDUCTAS A DIVO CLAUDIO ET POSTEA INTERMISSAS DILAPSASQUE
PER ANNOS NOVEM SUA IMPENSA URBI RESTITUIT.
This commemorates Vespasian repairing the Claudia in 71 AD. According to the inscription, the Claudia had been in ruins for nine years. Such a long interruption of the aqueduct after less than twenty years of use is a mystery. Perhaps the problem was upstream of the Claudia's junction with the Anio Novus channel, as the inscription does not mention repair of or damage to this aqueduct.
The third and lowest inscription on the Porta Maggiore is framed in a space below the two channels, giving the false impression of a third channel below. The channel that can be seen there is in fact the Acqua Felice, built in the 16th century. The inscription reads (CIL 6.1258):
IMP. T. CAESAR DIVI F. VESPASIANUS AUGUSTUS PONTIFEX MAXIMUS, TRIBUNIC.
POTESTATE X, IMPERATOR XVII, PATER PATRIAE, CENSOR, COS. VIII
AQUAS CURTIUM ET CAERULEAM PERDUCTAS A DIVO CLAUDIO ET POSTEA
A DIVO VESPASIANO PATRE SUO URBI RESTITAS, CUM A CAPITE AQUARUM A SOLO VETUSTATE DILAPSAE ESSENT, NOVA FORMA REDUCENDAS SUA IMPENSA CURAVIT
This was erected in honour of Titus restoring the Claudia in 81 AD, after the aqueduct was "ruined to its foundations from age". The fact that such restoration was required only a decade after the first repair raises questions about the quality of the initial construction.

Porta Tiburtina

The Porta Tiburtina was originally a monumental aqueduct crossing. Later it was made into a gate in the Aurelian Wall. The partitioning of the three channels above the arch is very similar in design to Porta Maggiore. The travertine facing of the middle channel shows the traces that the moulding of this original archway formed a pediment here. Caracalla chiselled this off for an inscription recording his restoration of the Marcia in 212 AD. There are, like the Porta Maggiore, three inscriptions of interest here. The first (CIL 6.1244):
IMP. CAESAR DIVI IULI F. AUGUSTUS PONTIFEX MAXIMUS COS. XII TRIBUNIC. POTESTAT. XIX IMP. XIIII RIVOS AQUARUM OMNIUM REFECIT.
This commemorates the restoration of the Marcia, Tepula and Julia by Augustus between 11 and 5 BC. The middle inscription, Caracalla's, is (CIL 6.1245):
IMP. CAES. M. AURELLIUS ANTONINUS PIUS FELIX AUG. PARTH. MAX. BRIT. MAXIMUS PONTIFEX \\MAXIMUS AQUAM MARCIAM VARIIS KASIBUS IMPEDITAM, PURGATO FONTE, EXCISIS ET PERFORATIS MONTIBUS, RESTITUTA FORMA, ADQUISITO ETIAM FONTE NOVO ANTONINIANO, IN SACREM URBEM SUAM PERDUCENDAM CURAVIT.
This refers to Caracalla's restoration work of 212 AD, which seems to have been quite extensive. It involved new arcades and tunnels, and the addition of a new source for the Marcia (the fons Antoninianus). The lowest inscription is (CIL 6.1246):
IMP. TITUS CAESAR DIVI F. VESPASIANUS AUG. PONTIF. MAX.
TRIBUNICIAE POTESTAT. IX IMP. XV CENS. COS. VII DESIG. IIX P.P.
RIVOM AQUAE MARCIAE VETUSTATE DILAPSUM REFECIT
ET AQUAM QUAEIN USU ESE DESIERAT REDUXIT.
This commemorates Titus earlier restoration of the Marcia, in 79 AD.

Aqua Traiani

Another important inscription is to be found in CIL 6.1260, which dates the construction of the Aqua Traiani to 109 A.D. This is particularly useful, as we have little documentary evidence for the Traiani.
AES[A]
[N]ERVAE . F . N[ERVA]
[T]RAIANVS . A[UG]
GERM . DACIC
[PO]NT . MAX. TR. POT. XI[II]
IMP . VI . COS . V . P .P
AQVAM . TRAIANAM
PECVNIA . SVA
IN VRBEM . PERDVXIT
EMPTIS . LOCIS
PER . LATITVD . P . XXX .

Miscellaneous inscriptions

CIL 1.808 is a valuable inscription that gives insight into the cost of construction in republican Rome.
OPERA . L[OC]
IA . CAECILIA DE . H
D . MIL . XXXV . PONTEM . IN . FLVIO
A . AD . TRIBVTA . EST . POPVLO . CONST
Q . PAMPHILO . MANCVPI . ET OPE
[V]IAR . T . VIBIO . TEMVVDINO . Q . VRB
REA STERNENDA . AF . MIL
[P]ENNINVM . MVVNIE[N]
XX PECUNIA . AD . tRIB[VTA]
ONST HS N[] . L[] RVFILIO L . L .I
[S]TI MANCUPI CVR . VIAR . T . T . VIP
[M]IL . LXX[]III . AD MIL . CX
LA INTERAMNIVM . V[O]
XX . PECVNIA . AD. TRI
LO . CONST . HS []
T . SEPVNIO . T . F . O
R . T VIBIO / - M
ARCVS DE LA
MANCVPI
Q VRB
Evidence for a number of items exists only in the epigraphic evidence. For example, CIL 15.7259 provides the only evidence for the existence of the Aqua Pinciana.
AQUA PINCIANA
D N FL VALENTINIA
NI AVG
CIL 6.33087 provides the only evidence for the existence of the Aqua Conclusa.
Q . POMPEIVS BITHYNICI . L . SOSVS
SATRIENA . P . L . SALVIA . VXSOR . FRVG
OPSEQVENTES . ET . CONCORDES . ESQVILEIS . AB . AQUA
CONCLVSA . FECER . SIREI ET . SVEIS . ET DIGNEIS
DVM . SVPPEDITAT . VITA . INTER NOS . ANNOS . LX . VIXIM VS . CONCORDES
MORTE . OBITA . VT . MONVMENT[]VM . HABEREMVS . FECIMVS . VIVI
STVDIUM . ET . ACME . L . VT . VNA . CONDEREMVS . CONDITIVOM
CVBICVLVM . FECERVNT
There are a number of inscriptions that link particular individuals to the aqueducts. Unfortunately, these inscriptions provide little information about the aqueducts themselves. An example of this kind of inscription is CIL 6.2344. This is a funerary monument set up by a public slave called Soter, and L. Calpurnius Flavianus, whose status is not made explicit. They dedicate the monument for their family, themselves and for their descendants.
Soter is specifically referred to as a public slave. As a castellarius, he would have been in charge of the castella of the Anio Vetus.
D . M
SOTER . SERVOS . PVBLICVS
CASTELLAR . AQVAE . ANNIONIS
VETERIS . FECIT . CONIVGI . BENE
MERENTI . ET . L . CALPVRNIVS
FLAVIANVS . MATRI . BENE
MERENTI . SIBI . ET . SVIS
POSTERISQVE . EORUM
An example of a cippus is provided by CIL 6.1250c.
MAR
IMP . CAESAR
DIVI . F . AVGVSTVS
EX . S . C
C inftyXX . P CCXI