ROMAN PROVINCIAL CITIES 411
A wall was eventually built around the city in the early third century, including along the riv-
erfront. Two sides of the northwest fort were incorporated into this defensive circuit. The area
enclosed was 132ha, making it the largest town in Roman Britain. This fortification, replete with
added towers, would continue to serve the town into the Middle Ages.
A major find from Roman London was the Mithras Temple, excavated in 1953–54 along the
east bank of the Walbrook. Dated to the late second century, this temple was devoted to Mithras,
a god probably of Persian origin. The cult was secret; initiation, for men only, was required. The
cult was popular especially among the army stationed along the empire’s frontiers, but also in
Rome and its port, Ostia. After the fourth century, its popularity quickly waned. Mithraic beliefs
are imperfectly understood. Texts do not reveal much, so our understanding has depended on
interpretations of images and of the remains of buildings. Mithraic temples were built and deco-
rated to resemble caves. Indeed, the example from London was partially underground. The key
event in this religion is Mithras killing a sacred bull, an event regularly depicted in the temples.
Also frequently shown is a banquet that Mithras and Sol, the sun god, share beside the body of
the slain bull. The precise meaning of these events is uncertain, even if most would view them as
acts of sacrifice with cosmic significance.
TRIER (AUGUSTA TREVERORUM)
We end with Trier, a city of great political, cultural, and economic significance in, especially, the
third and fourth centuries. Trier lies on the Moselle River in south-west Germany, in territory
occupied in pre-Roman times by the Germano-Celtic Treveri tribe (or civitas, the Roman term for
tribe). One hundred km to the north, the Moselle joins the Rhine River, the natural feature that
for centuries defined the north-west frontier of the Roman Empire. Founded under Augustus
as an army camp, Trier eventually became the political and commercial center of the north-west,
today’s north France, Belgium, Luxembourg, and Germany west of the Rhine. The headquarters
of the procurator, the regional financial official, and, from 337, the praetorian prefect, the top legal
officer, were located here; businesses included the wine trade, and the manufacture of pottery,
textiles, and weapons. In addition, in the late third and fourth centuries, the city served as an
imperial residence, and became a cultural and religious (Christian) center. With these distinc-
tions, Trier had an importance far greater than Nîmes or London. This status is reflected in its
architecture. In 395, however, the Romans abandoned Trier as an administrative center, for secu-
rity reasons: military confrontations were increasing in the Rhine frontier zone. Soon thereafter,
in the early fifth century, the city was taken over by the Franks, one of the Germanic tribes that
would conquer the western Empire.
Little is known of the city’s remains during the first century. A bridge on pilings and the pos-
sible beginnings of the grid plan may date to this period. In the second century, building activ-
ity was extensive (Figure 24.17). A grid plan is now attested, with, in the center, a large forum
(400m × 100m) with a sunken cryptoporticus, an underground gallery. Other structures from this
century include a stone bridge; a huge bath complex near the river (the St. Barbara Baths, named
after a church nearby); a sacred district of perhaps pre-Roman origins, Altbachtal, consisting of
cluster of over fifty shrines; and an amphitheater on the eastern edge of the city, with a capacity
of 20,000.
The important political status of the city is seen best in grand buildings erected during the later
empire. They include the Porta Nigra (“black gate”), the monumental Imperial Baths (Kaiser-
thermen), and the Aula Palatina (“palatial hall”), also known as the Basilica of Constantine. This