An emperor should never admit when he's wrong. But it seems that my knowledge of the Roman frontier (or "limes") along the middle Danube was deficient.In an earlier post, I suggested that the only Roman military remains in Croatia were the pre-Flavian legionary fortresses at Burnum (near Kistanje) and Tilurium (Gardun). Located in the Adriatic province of Dalmatia, in the far west of Croatia, they are almost 200 miles from the imperial frontier.
In my own defence, I can only point out that, besides a one-year governorship of Asia in AD 135, I have never set foot out of Italy, and have no military experience whatsoever! Nor is geography my strongest subject. So it is perhaps understandable, if not entirely forgivable, that I was unaware of one important fact: namely, that 188 km of the Croatian border in the east is marked by the river Danube (as an anonymous correspondent kindly informed me).
For much of its course, the Danube marks the northern limit of the Roman empire, flowing east through Austria and Hungary to the great bend above Budapest, whereupon it turns south, eventually entering Croatian territory between the rivers Drava and Sava, before turning east again at Belgrade and (having traversed a series of spectacular gorges) wending its way through Serbia, Romania, and Bulgaria to the Black Sea coast.
This sector of Roman frontier is apparently awaiting recognition as a World Heritage Site. Forts are known at Batina Skrela (Roman Ad militares), Osijek (Mursa), Dalj (Teutoburgium), Sotin (Cornacum), and Ilok (Cuccium), but the remains have yet to be developed for public viewing. Let us hope that World Heritage Status will provide the impetus.