There are two Roman watch-towers at Shiehill in Tayside, located to either side of the main military highway into north-east Scotland. The southernmost tower (Shiehill-South) lies to the west of the road while the northern tower (Shiehill-North) lies to the east. Both of these fortifications consist of a four-post watch-tower enclosed by an earthen rampart surrounded by two external ditches and an entrance facing the road. The two watchtowers lie ? metres apart, Shiehill-South some ? metres north of the similar watch-tower at Ardoch, while Shiehill-North lies ? metres to the south of the fortlet at Kaims Castle.
The regular spacing of these small fortifications along this particular stretch of the military road into the north-east, and others along the Gask Ridge constitute the first planned military frontier in Britain, the precursor of both Hadrian's Wall in northern England and the short-lived Antonine Wall in southern Scotland.