The Gask Ridge system was a Roman fortification system constructed along the Gask Ridge to the north of Stathearn in Perthshire, Scotland.
It was built sometime in the 80's AD and consisted of a series of forts and watch towers stretching from modern Glenbank, (to the north of Dunblane) to Bertha (which lies just upstream from Perth) and is now believed to be the first ever Roman fortified land frontier.
Forts were located at Ardoch, Strageath and Bertha with at least 15 intervening timber watch towers each around 9 feet square, surrounded by a rectangular rampart and a circular ditch which were probably at least two storeys high.
It is generally believed to have been constructed to protect the road into what is now northern Scotland to support further Roman advances into Caledonia proper. However in 85 AD the tribes in Dacia revolted against Roman rule and the Legio II Adiutrix was removed from Britain to assist in putting down the rebellion.
Legio XX Valeria Victrix was withdrawn from the northern frontier and the Gask Ridge system was abandoned as the Romans fell back to a makeshift defence line along the Stangate Road.
Sources of further information:
http://www.morgue.demon.co.uk/Pages/Gask/index.html
www.stud.uni-muenchen.de/~erik.dobat/gask/gask2.htm