Located on Roman province of Dacia, present-day Romania, the Limes Porolissensis was a defensive line organized on 2nd century AD after the Conquest of Dacia, having observations towers, short cut-off walls fortifications, integrating the following castra: Castra of Negreni Castra of Buciumi Castra of Largiana Castra of Certinae Porolissum Castra of Jac Castra of Tihău Castra of Samum Castra of Arcobara Castra of Livezile Castra of Orheiu Bistriței Castra of BrâncoveneștiThe limes was a complex network of over 100 towers, fortlets, walls and forts disposed in a line over 200 km from the Apuseni Mountains to the Eastern Carpathians, following the highland chain of the Meseș Mountains. Wikipedia