Excavations on the "Bloskopf" near Bad Ems on the River Lahn yielded a Roman military installation of about 0.1 ha in size of the Claudio-Neronian period. In the inner V-shaped ditch pointed timbers in the style of an obstacle of approach were proven for the first time in situ and in an excellent state of preservation. In analogy to the pila muralia, these are called "pila fossata", a term hitherto not recorded. The military installation formed part of a linear ditch-and-rampart system and probably served as a barrier in the terrain. An area of mine shafts and finds of slag from Roman contexts indicate a connection with mining activities. The proof of a Roman date for these mine shafts is still lacking.