Castra Martis, the Late Roman Fortress in the Town of Kula
Castra Martis, the “fortresses of Mars”, is a late Roman fortress whose remains stand in the centre of Kula, a town in Vidin Province in north-western Bulgaria. It guarded the road through the Vrashka Chuka pass, the north-westernmost pass of the Balkan Mountains. A very well-preserved square fort with corner towers is its main attraction.
The town of Kula is named after the tower of a Roman fortress dedicated to the god of war. The fortress guarded a mountain pass, was taken by the Huns in 408 and had a bishop at a church council.
The history of Castra Martis
The fortress stands on the steep southern slope above the gorge of the Voynishka river, in the middle of today’s town of Kula. Archaeological work showed that a small Thraco-Roman settlement had existed on the same slope since the first millennium BC, before any fortress was built. The Latin name Castra Martis means “the fortresses of Mars”, after the Roman god of war. In the 1870s the Austro-Hungarian scholar and traveller Felix Kanitz identified the imposing ruins in the centre of Kula as the ancient Castra Martis.
The fortress was part of the restored Danube limes of the Roman Empire after the loss of Dacia at the end of the third century. It was probably built by Emperor Diocletian at the turn of the third and fourth centuries, and it protected the road from Bononia to Singidunum through the Vrashka Chuka pass. It lay in the province of Dacia Ripensis and became important enough to be the seat of a bishop, a suffragan of the provincial capital Ratiaria. Its only recorded bishop, Calvus, took part in the Council of Serdica in 343.
The fort appears in the written sources several times. In 377 Emperor Gratian passed through it with his troops on the way to Thrace. In 408 the Huns under Uldin took control of the site during an attack on the Eastern Roman Empire, apparently by treachery, but held it only briefly. In the sixth century Procopius of Caesarea listed Castra Martis among the fortresses that Emperor Justinian I (527–565) rebuilt on a large scale. It was destroyed during the Avar invasions of 586–587, and in the thirteenth and fourteenth centuries the fortification was partly restored and used for the defence of the Vidin Tsardom.
The complex has two parts. The first built was a small square fort of the quadriburgium type, dated to the end of the third and the beginning of the fourth century, when Diocletian was busily building such forts in the border regions. It measures 40 by 40 metres and has large corner towers 12.5 metres in diameter. Its walls, 2.2 metres thick, were made of stone and triple courses of brick. South of it lies the larger castle, a military camp that was strengthened under Constantine the Great with walls 4.3 metres thick. The castle forms an irregular quadrilateral with seven polygonal towers and covers 15.5 decares. The foundations of a Roman bath to the north-west show that civilians also lived outside the walls.
Curious facts about Castra Martis
- The south-eastern tower of the fort rises 16.3 metres and gave its name to the modern town: Kula means “tower”.
- The name Castra Martis can be read as “the fortresses of Mars”, a reference to the Roman god of war.
- The quadriburgium is described as very well preserved and fully uncovered, and its walls still stand to an average height of 2 metres above the floors.
- The fort could be entered only from the south, through a gate with a two-leaf door; later in the fourth century a narrower wall was added in front, forming guardrooms and a gate tower.
- In the Middle Ages, in the thirteenth and fourteenth centuries, the old fortification was partly restored to help defend the Vidin Tsardom.
- Castra Martis Hill on Livingston Island in Antarctica is named after the fortress, and the old bishopric survives today as a Latin Catholic titular see.
Tours near Castra Martis
Experiences in the area that you can book online with Viator:
Visiting Castra Martis: what to expect
- The remains stand in the centre of Kula, so the fortress can be combined with a stroll through the town.
- Look for the square quadriburgium with its four large corner towers and the single gate on the southern side.
- South of the fort are the walls and seven polygonal towers of the larger castle on the slope above the river gorge.
- The sources say nothing about visiting arrangements, so check the current opening hours and access before you go.
- Other places of this guide in the area include the Albotin Monastery, about 12 km away, and Magura Cave, about 20 km away.
Opening hours, access and conditions can change. Check before you go.
Map: where Castra Martis is
Questions
What is Castra Martis?
Castra Martis is a late Roman fortress in the town of Kula in north-western Bulgaria. It guarded the road through the Vrashka Chuka pass and later became a bishopric.
Where is Castra Martis?
The remains lie in the centre of the town of Kula, in Vidin Province, on a steep slope above the gorge of the Voynishka river.
Who built Castra Martis?
The small fort, the quadriburgium, was probably built by Emperor Diocletian around the end of the third century. The larger castle was fortified later, under Constantine the Great.
Why is the town called Kula?
The name comes from the 16.3-metre south-eastern tower of the Roman fort, since kula means “tower”.
What happened to the fortress?
The Huns under Uldin briefly took it in 408, Justinian I rebuilt it, and the Avars destroyed it in 586–587. In the thirteenth and fourteenth centuries it was partly restored.
Was Castra Martis a bishopric?
Yes, it was a see in the province of Dacia Ripensis, and its bishop Calvus attended the Council of Serdica in 343. Today it remains a Latin Catholic titular see.
Also nearby
Albotin Monastery
Deleyna · 14th-century rock monastery and Easter dances
12 km away
Magura Cave
Belogradchik · cave of 750 prehistoric paintings made of bat guano
20 km away
Baba Vida
Vidin · the best-preserved medieval castle in Bulgaria
31 km away
Belogradchik Fortress
Belogradchik · Roman-era fortress using towering natural rock
32 km away