A Roman practice camp is located on the open land of Gelligaer Common. The earthwork lies on raised ground between two marshy areas. When visited in 1991 bracken from the surrounding ground had just been harvested leaving the earthwork as a bracken-grown promontory. Overall the earthwork measures 25m (north-east by south-west0 by 20.7m. It is defined by a bank up to 6m wide and 0.9m high.There are opposing entrances in the north-west and south-east sides. ; that on the SE is marked by an internal clavicula.
A short distance to the east is a second likely practice work (see NPRN 308506). Others (actual and possible) lie on nearby enclosed land around the fringes of the common.
Additional sources:
Ordnance Survey record: ST19NW9.
RCAHMW air photos: 94-CS 0769; 945105/50

David Leighton, RCAHMW, 1991