Rediscovered in 1972, this fort is located to the north of Paisley on low hills overlooking the Clyde Estuary, known in Roman times as the Clota Flumen. The fort has been associated with the fourth campaign season of governor Gnaeus Julius Agricola and was founded sometime in either 80AD or 81, along with other fortifications at Elginhaugh and Mollins. It encloses an area of about 3¼ acres (c.1.3 ha) and was oriented towards the west. The rampart was about 15 feet (c.4.5 m) wide, constructed of turf fronted by a timber palisade and revetted at the back with clay. The northern defensive ditch was found to be around 10-12 feet wide but only 1½ feet deep (3-3.5 x 0.4 m). There was an annexe of about 1 acre (c.0.4 ha) attached to the eastern side of the fort.
Two pottery fragments recovered from the fort environs bear the stamps of the potters ALBINVS and SVMACI, both known to have been productive during the Agricolan period, thus giving an approximate date of construction for the fort. A number of bronze asses dated to the year 86AD have been uncovered at Barochan. These coins were in almost mint condition, proving that they had been in circulation for only a short period. It would seem that the fort was occupied at least until this date or shortly thereafter before being demolished and the garrison withdrawn.
The Antonine fort at Bishopton (NS4172) lies only 1¾ miles to the north on the shores of the Clyde Estuary, overlooked by the site on Barochan Hill.