Many Roman forts had four gates, but Maastricht’s castellum had only two: an eastern and a western gate. Their placement followed the line of the Via Belgica, which entered from the east via the Meuse bridge and exited westward toward Tongeren. By the 4th century, the earlier north–south route was no longer in use, so no gate was constructed in that direction.
The road running through the castellum was laid with gravel rather than stone slabs, which was typical for smaller regional centres in this part of the Roman Empire. Like other stretches of the Via Belgica, it consisted of a thick gravel layer up to 1.5 metres deep and around eight metres wide, with a raised central ridge known as a talus or agger to allow rainwater to drain from the surface. Outside the settlement, the road was bordered by an additional eight meters on either side and bounded by a ditch (Verhagen and Jeneson 2012; Dijkstra & Flamman 2004).