Roman forts

Forts are the most rewarding Roman sites to visit in this region, for a simple reason: they were built where nobody wanted to live afterwards. A town gets rebuilt over for two thousand years; a fort on a pass gets abandoned, overgrown and left alone. What you find is often the real thing, wall cores standing to shoulder height in the woods, rather than a reconstruction.

Most of the forts here belong to one system. The Claustra Alpium Iuliarum, the “barrier of the Julian Alps”, was a late Roman defence between Italia and Pannonia that protected Italy from invasion from the east. It was not a single wall but a series of interconnected fortifications securing the Postojna Gate, the land link between the eastern and western halves of the empire. Its centre was Castra ad Fluvium Frigidum at today’s Ajdovščina; other principal fortresses were Ad Pirum on the Hrušica plateau and Tarsatica at Rijeka. Fortifications were raised gradually after the Illyrian revolt of AD 6, but most of the construction came after 284 under Diocletian and Constantine. Ad Pirum, the hill fort at the heart of the line, was typically manned by about 500 soldiers.

Under “fort” we group everything from a garrison fortress like Ad Pirum to small watchtowers and stretches of barrier wall with a tower attached. Each entry aims to say how much wall is standing, how far the walk is from the nearest road, and whether the site is marked. Many of these places are on high ground and can be under snow for part of the year, so check the entry’s visiting notes before you go.