Seen on the Britarch list (from Peter Green):

Archaeologists working on Scotland’s Gask Ridge Frontier, which dates to the early 70s AD, have discovered evidence that part of the visible monument is in fact 70 years younger than previously believed and dates from the Antonine period. The Gask frontier is the oldest Roman frontier anywhere in the Empire and predates Hadrian’s Wall by 50 years

The Gask Ridge Frontier is a combination of forts, watch towers and a road. It stretches from around Dunblane in Perthshire to north of Perth itself, mainly running on the low Gask Ridge. Work this summer, by the Roman Gask Project, University of Liverpool, indicates that the visible Roman road is younger than the watch towers that are arranged along it. The towers date from around 70 AD and would have been linked by a road or track, however the visble road is Antonine in date (around 140 AD).

During the Antonine period Hadrian’s Wall was abandoned and a new frontier of wood and turf – the Antonine Wall – was built between the Clyde and Forth. At the same time some of the forts that made up the Gask system were rebuilt as outposts of the Antonine Wall.

“The archaeology of the Gask is becoming more complex than originally believed and shows that it played an active part in the military history of Roman Scotland for a considerable time,” said Dr David Woolliscroft co–Director of the project.

“The watch towers must have been linked by a road or track, to allow the tower teams to reach their posts from the nearby forts, but that road remains to be found. The wonderfully engineered road we see today was built later when the forts came back into use in the mid 2nd century.”

The combination of road and watch towers that was first created in Scotland was used as a model by the Roman army in Germany 20 years later when they built their frontier from the Rhine to the Danube.

Roman Gask website