Moles manuque adiutum: On the Embankment Walls of the Tiber Island

Andrew G. Nichols

University of Florida

Livy 2.5 provides the earliest (and in many ways, the only) description of the Tiber Island in ancient literature. After briefly discussing the island's formation, the historian gives a thumbnail sketch of its architectural development. Interestingly, he chooses to emphasize how the site was enlarged and reinforced with embankments in order to support temples and colonnades:

insulam inde paulatim, et aliis quae fert temere flumen eodem invectis, factam; postea credo moles manuque adiutum, ut tam eminens area firmaque templis quoque ac porticibus sustinendis esset.

It is not unlikely that in his rather selective reconstruction of the island's early architectural history, Livy was influenced by events and concerns of his own time.

Between the late Republic and the early Empire, the city of Rome underwent a period of expansion which lead to the urbanization of large tracts of floodplain on both sides of the Tiber. The areas which were mainly affected by this process were the southern Campus Martius and the Transtiberim district. Located between these two developing areas, the Tiber Island experienced a corresponding period of growth.

Sometimes in the second quarter of the first century BCE, a new temple of Aesculapius was built to replace the original structure of 291 BCE. The island was also provided with two bridges in masonry which connected it permanently to the mainland. The first was a replacement of a former wooden bridge which had joined the island to the Campus Martius since early times. It was completed shortly after the new temple of Aesculapius in 62 BCE. The second bridge, which reached over to the opposite shore of the Tiber, was created anew a few decades later to carry the traffic to and fro the newly developed Transtiberim district.

The need to build bridge abutments on both sides of the island called for a substantial reinforcement of its shores. A new system of retaining walls, encompassing the entire perimeter of the site, was completed in the second half of the first century BCE. This construction was part of a larger series of renovations which also affected the riverfront on both sides of the Tiber. As the city grew towards the river and beyond, so did the need for an upgraded infrastructure which could support this growth.

Substantial sections of this massive wall system in squared stone masonry survived both along the river banks and on the island itself until the late nineteenth century, when they were obliterated by the construction of the new Tiber embankments (the so-called Muraglioni.) Today, the only extant remains from these imposing structures are found on the east shore of the Tiber Island, at the southern end of the site and at the junction with the Pons Fabricius. Despite their evident value for our understanding of the city's riverfront in Roman times, no archaeological study exists to this day of these two wall segments. Similarly, no attempt has been made to collect and interpret the extensive pictorial evidence showing the ancient Tiber embankments as they were before their destruction in Victorian times. The Tiber Island Survey Project, now in its eight year of existence, devoted part of the 2004 Summer campaign to the completion of these two objectives. This presentation offers an illustrated summary of our final results, tracing a comprehensive new picture of the Tiber Island and the lower Campus Martius riverfront at the time of their maximum development between the late Republic and the Principate.