At the Prosjanice site, near the Danube River in Čortanovci the remains of the Roman fort called Ad Herculem can be found.
Once there was a stone fort (the largest in this part of the Danube limes), which protected a broad area from Cusum – (Petrovaradin) to Acumincum -(Slankamen), and further up to Rittium – (Surduk).
According to the coins that were found there, the fortress was built probably in late third or early fourth century. The fort existed until the end of the fourth century, but it was burnt during the attack of the Barbarians. It has never been rebuilt.
The circular wall of south-east tower (more than ten meters in diameter) which is just over a meter high as well as the walls of the main bulwark, nearly two meters wide, ranging from the tower to the west – northwest, can be seen today on the Prosjanice site. It has been determined by researches that a part of the fort is located in the bed of the Danube (the two towers and the northern wall).