Located in present-day Romania, Limes Porolissensis was the frontier of the Roman empire in Dacia Porolissensis, the northernmost of the three Dacian provinces. It was a defensive line dating from the 2nd century AD after the Conquest of Dacia up to the retreat of the Roman army from the region. The Limes was a complex network of over 200 observation towers, fortlets, palisades and ditches, and forts disposed in an arched line following the highland chain of the Meseș Mountains over 200 km from the Apuseni Mountains to Bistrița Mountains,[2] and required as many as 16,000 soldiers to man and defend.[3]
The Limes is named after its key defensive point: Porolissum.[4]
It also integrated the following forts: Rucconium, Docidava, Largiana, Certiae, Castra of Jac, Castra of Tihău, Castra of Samum, Castra of Arcobara, Castra of Livezile, Triphulum, and Castra of Brâncovenești, and was supported by the castra of Ulpianum, Optatiana, Gherla, as well as being connected to the larger forts of Napoca and Potaissa.[5]
Sections of the Limes were first discovered during the nineteenth century by the reputable Hungarian historian Károly Torma. Torma's research started from a misinterpretation of an inscription from Samum used in the construction of a local castle from which he took the expression "reg(ione) (tr)ans vall(um)" as indicating a "regio transvallum".[6]