A 200' aerial view of the Bar Hill Fort ruins near Kilsyth, Scotland.  The fort was established by the Romans around 142AD during the construction of the 39-mile Antonine Wall by emporer Antoninus Pius as the northerly frontier of the Roman Empire, further north than Hadrian's Wall which was completed some twenty years earlier.  However the wall was difficult to maintain & the Romans eventually retreated back to Hadrian's Wall by 162AD leaving the fort abandoned.  Much of the Antonine Wall is faded however small sections still exist such as here where it is seen as a turf fortification w/ a deep ditch on the north side.