Type: Fort, Camp, Camp
This large fort at the mouth of Glen Ard was probably built during the administration of governor Sallustius Lucullus probably during 85AD as part of a series of military installations known as the Glen Forts. The lifetime of the fort was very short, perhaps being occupied for only a single season before being dismantled and abandoned.
The fort was discovered from the air by J.K. St. Joseph in 1968. It lies on a level platform 20 ft. above the western shores of the Lake of Mentieth, and its major axis is aligned from south-west to north-east. The area between the ditches measures 600 ft. by 490 ft. (183 x 150 m) and encloses an area of about 6¾ acres (2.7 ha). The fort is defended by a system of double ditches, normally set a regular 5 ft. (1.5) apart with a wide berm before the rampart for most of the perimeter, but curving inwards and joining at an acute angle at each gateway. A section across the defences on the north-west revealed two V-shaped ditches, the outer measuring 12 ft. wide and 5 ft. deep (c.3.7 x 1.5 m), the inner only 10 ft. by 4 ft. (c.3 x 1.2 m), though it is very likely that the inner ditch had been damaged here by ploughing, which has also entirely removed all traces of the rampart.
An irregular annexe on the north-east side of the fort was formed by extending the ditches from the north and east angles down to the shores of the lake. There are no traces of the double ditch system of the fort on this side, and it is possible that none was ever present, the shores of the lake here sloping upwards unbroken to the north-eastern rampart within the protective defences of the annexe. The annexe measures approximately 500 ft. across the face of the fort and about 300 ft. down to the edge of the lake (c.150 x 90 m), enclosing an area just under 3½ acres (c.1.4 ha).
There is a marching camp to the immediate south-east of the fort at Menteith and another to the north-west at Malling.