The southern Roman camp at Burnswark measures c. 290m by 210m, with three entrances on the north, each guarded by a roughly circular mound about 18m in diameter at base. Known locally as "The Three Brethren", it was suggested by R G Collingwood that they were artillery platforms for attacking the fort, though he was unable to cite any parallels. It has also been suggested that the camp is actually a training camp, for realistic practices with missile weapons, long after the native fort had been abandoned.
The other sides of the camp have central gateways, guarded by normal traverses.