The ancient road “Via Traiana”, connecting Rome with the Eastern provinces of the Empire and the Middle East, passes through the territory of Troyan municipality. It is one of the longest and most well-researched Roman roads in Bulgaria. The first Roman road constructions on the already used Thracian roads dates back to the reign of Emperor Nero (69 AD), but the final route of the road is associated with the name of Emperor Trajan (98-117 AD) whose name, through the name of the road, passes over the present town of Troyan. Passing through Hemus Mountain, the road connects Lower Moesia province with Thrace. Along the road, from Eskus to Philippopolis, numerous road stations, settlements, fortifications and observatories are built. They contain military units whose main purpose is to observe and defend this important commercial and military Roman road.
In addition to the well-preserved Sostra fortress, tourists can also see remains of two other road stations on the Troyan territory - Ad Raditses (near Beli Osam village) and Montemno (near the Troyan pass).
To a great extend the present Troyan pass passes through the trails of this ancient Roman road.