Roman Fortress Castra Martis

After the Roman Empire conquered the territories between the Balkan Mountains and the Danube in the first century AD, Castra Martis was established as part of the fortified Danubian Limes. Its purpose was to protect a road connection over the Vrachka Chuka Pass. With the empire's expansion into Dacia under Emperor Trajan, the fortress temporarily lost some of its significance. In the late 3rd and early 4th centuries, after the withdrawal from Dacia, the Lower Danubian Limes, including Castra Martis, was reinforced. The fortress was an episcopal see, and its bishop Calvus participated in the Council of Serdica in 342. In 378, the Western Roman Emperor Gratian sought refuge here on his way to the Battle of Adrianople. In the early 5th century, around 408 or 409, Castra Martis was captured and plundered by the Huns under Uldin. The Goths also damaged the fortress in the 4th century. According to Procopius of Caesarea, Emperor Justinian I had the fortress rebuilt in the 6th century against Slavic invasions, but it was conquered by Slavs and Avars in the same century. Its final destruction occurred during the Avar invasion of 586/587. In the 13th and 14th centuries, during the Second Bulgarian Empire, the fortress was re-fortified and served as a defensive bulwark for Vidin, until it was finally destroyed by the Ottomans in 1396.

The Roman Fortress Castra Martis is located in the city of Kula, in the Kula district, in the Vidin region of Bulgaria, at an elevation of approximately 284 meters above sea level.

The ruins of the castellum can be explored. In the city of Kula, there is also a local history museum displaying artifacts from the fortress and a miniature model of Castra Martis. The current name of the city Kula is derived from a still-preserved tower of the fortress.