Overlooking Drumchapel is the Roman fort at Castlehill. Its presence is marked by a circle of beech trees. It was once thought that the fort lay entirely in the tree-circle but aerial photography has shown that it also lay partly on sloping ground to the east. A raised plateau on the northwest of the tree-circle may be the site of a mile-fortlet. Anne S. Robertson's The Antonine Wall notes: "The summit of Castlehill lies almost 400 feet (120m) above sea-level. It has one of the finest prospects of any fort-site on the Wall. Besides the view north to the hills and eastwards along the line, there was a wide outlook westwards and south-westwards over the estuary of the Clyde to the Renfrewshire coast."
The fort was manned by a cohort, deployed in the front line of the Antonine wall, ahead of the legions (or heavy infantry). The cohort would have comprised auxiliaries; non-citizens of the Roman Empire who would only gain citizenship after 25 years military service. Cohorts were named after the auxiliaries' origin; the 4th Cohort of the Gauls serving in Drumchapel. Although much effort went into ensuring cohorts recruited from their original area, at such a distant point of the Roman Empire, local people would also have been conscripted. A typical Auxiliary regiment would contain around 500 men; six 'centuries' of 80 men for an infantry unit. Any regiment though would rarely be at full strength through sickness and in providing men to assist in civil administration; local conscription was a necessity to provide any defensive cover. Traditions die hard in most regiments, however, and in Drumchapel local conscripts would take on Gallic customs and beliefs.
An altar honouring the 'Goddesses of the Paradeground' was found in 1826 (NS 5260 7271) measuring around 41 inches in height and 15 inches in breadth. It is inscribed "CAMPES.TRIBVSET.BRITANNI.QPSETIVS.IVSTVSPREF.COH.IIII.GAL.V.S.L.L.M" meaning "To the eternal field dieties of Britain, Quintus Pisentius Justus, Praefect of the 4th Cohort of the Gaullish Auxilliaries dedicates this his vow being most willing fulfilled."
Following unauthorised metal detecting at the site, a site inspection by Historic Scotland found small holes - and a roman mason's pick now donated to the Hunterian Museum, University of Glasgow.