Roman castrum (camp) Diana was built on a high rock above the Danube, Karataš, at the village of Sip near Kladovo. Construction of the earliest earth-wooden fortification is related to the arrival of the first military formations at the Danube in the early 1st century and the Emperor Trajan. It was finished at the same time as the digging of the Sip canal (the year 101) which eliminated the biggest obstacle to navigation on the Danube.

It got its final shape at late 3rd and early 4th centuries by adding the ramparts which start at angles and go towards the Danube, closing and protecting part of the bank. In the middle of the 5th century it was destroyed by the Huns; it was reconstructed by Emperor Justinian around the year 530. The fortification was also destroyed during Slav and Avar incursions in the late 6th and early 7th centuries. Outstanding archaeological material (various items from everyday life of the time, sculptures of marble and bronze), show that besides its role for the defence and protection of the canal, during six centuries Diana was also an important economic centre with a harbour and a pier.