On the heath near Ermelo lie the remains of a Roman army camp. The contours of a rampart and ditch are still clearly visible in the landscape. The camp was probaly constructed bewteen 150 and 200 CE. The size is approximately 9 hectares, which could accommodate 6,000 to 8,000 men . The camp was located about 35 kilometers north of the Limes, the border of the Roman Empire.

The camp was most likely a marching camp, a temporary fortification that was built in enemy territory . It might have been constructed to support a military expedition against Germanic tribes who had settled north of the Limes. This camp is the only known Roman marching camp in the Netherlands.