While the castellum on the western bank of the Meuse River in Maastricht is relatively well understood, the picture is far less complete on the opposite bank of the Meuse. Historical accounts and strategic logic strongly suggest a defended bridgehead or associated settlement on the east side, since it would be unusual to guard a major river bridge from only one bank. Yet no substantial late Roman fortifications have been securely identified there, leaving this part of the reconstruction necessarily speculative.
The interior of the fort also presents challenges. Excavations indicate earlier Roman occupation on the site, including a bathhouse, buildings and a sanctuary or temenos whose structures were later partly demolished and quarried for building stone when Constantine’s new walls were erected. However, only segments of these phases are preserved, and the internal layout of the 4th‑century castellum remains difficult to reconstruct in detail.
Fragmentary evidence from smaller excavations shows additional 4th century activity within the castellum. These remains suggest a mixture of new construction, re‑use of earlier Roman structures and perhaps even the presence of standing ruins from the earlier settlement. However, much of the interior remains unknown, and future discoveries may significantly alter our understanding of how the fort functioned.