Mitreo di Cosa

TNMM 75

Very likely due to its modest nature, the Cosa Mithraeum has been mentioned in scholarly publications only four times – each in passing – since its discovery in 1954. This sparse attention, restricted solely to literature on Cosa, has meant that the mithraeum is well-known among those intimately familiar with the colony, but has languished in complete obscurity among Mithraic scholars for the past half century.

[... The mithraeum] is located in the basement of the curia, which, together with the comitium, constitutes the earliest structures in Cosa’s forum. The pair of connected buildings was built shortly after Cosa’s founding in 273 BCE (fig. 1). The earliest phase of the present curia consisted of a single, two-story room on axis with the comitium, built with the same large, polygonal limestone blocks that comprise Cosa’s walls. The building was built on the side of a slope beside the comitium, meaning that the entrance to the building was on the second floor, facing the comitium (SW). The lower floor would have been accessed by stairs, and was likely used for the keeping of records.

In 197 BCE, a second wave of colonists arrived, leading to substantial renovations of the complex. Between 175 and 150 BCE, the original, single room curia was replaced by one with three chambers. These new wings shared their inner walls with the original structure, but were expanded with walls of mortared rubble. Like the original central structure, both of these additions contained two stories. The basements were floored with rammed earth, while wood beams in the ceilings provided support for the floors above. The second stories of the two new wings were accessed, like the central hall, through doorways that opened to the comitium. In his description of this phase, Richardson admits that it was unclear whether or not these new rooms communicated with one another via internal doorways. Richardson further suggests that during the Republican and early imperial periods, these new additions may have served as offices for the duumviri and aediles of the colonia.

The installation of the mithraeum in the basement of the structure marks the final phase of renovations. The dating of these renovations has been the subject of some debate, and will be addressed momentarily. Aside from the rubble-filled benches mentioned previously, Richardson also found small niches in either bench lined with roof tiles (no longer extant), as well as large blocks of brick and mortar constructed within each bench, possibly for supporting statues. Another base was found at the end of the SE bench, and another in the western corner of the room. At the rear of the room, about 70 cm from the rear wall, Richardson found an “altar”, 60 cm on either side, and 1.2 m high, of similar construction to the two blocks in the benches. On the ground in front of this altar is a “ritual” well lined with mortar. Richardson found traces of plaster lining the rear wall behind the altar, some of which is still extant half a century later. He suggested that the plaster comprised part of a frescoed tauroctony that matched the modest nature of the small room.