Traces of the Roman Empire along Bulgaria’s Danube River are often hidden beneath modern buildings, farmland and riverside vegetation. Yet the remains of ancient cities, fortresses and roads tell the story of a time when this region formed part of one of the most extensive frontier systems of the ancient world: the Danube Limes.
The Dunav Ultra cycling route passes through or near many of these historic sites, including several featured among the 100 Dunav Ultra Highlights. This guide explores five remarkable places: Ratiaria near Archar, Oescus near Gigen, Dimum in Belene, Novae near Svishtov and Durostorum in Silistra. Together, they reveal a fascinating chapter of Roman history and add another dimension to a cycling journey along the Danube.
The Danube Limes: The Frontier of the Roman Empire
The Danube Limes formed part of the Roman Empire’s vast network of fortified frontiers. Along the Lower Danube, east of the Iron Gates gorge between present-day Serbia and Romania, construction began in the 1st century AD and continued over the following centuries. The frontier included legionary fortresses, smaller forts, watchtowers, roads, river ports and settlements that supported military and economic life.
The Danube provided a natural barrier against attacks from the north, but it was also a vital transport corridor for troops, goods and building materials. Trade developed along both banks, while settlements, workshops and markets grew around military garrisons.
In AD 86, the Roman province of Moesia was divided into Moesia Superior (Upper Moesia) and Moesia Inferior (Lower Moesia). The boundary between them followed the Tsibritsa River in what is now northwestern Bulgaria. Today, cyclists following Dunav Ultra cross the Tsibritsa on a bridge along the route towards Kozloduy. Ratiaria belonged to Upper Moesia, while Oescus, Dimum, Novae and Durostorum were part of Lower Moesia.
Administrative reforms in the late 3rd and early 4th centuries reorganised these territories into new provinces, including Dacia Ripensis and Moesia Secunda.
Over the centuries, sections of the Danube frontier were repeatedly destroyed and rebuilt. Its eastern sector remained in use into the early Byzantine period, until the beginning of the 7th century. The history of this remarkable frontier spans almost 600 years.
Did you know? The Romans marked distances along their roads with stone milestones known as miliaria. These were generally placed one Roman mile apart, approximately 1,480 metres. Inscriptions recorded the name of the emperor and the distance to a town or important road junction. Milestones helped travellers navigate and identified roads built or repaired under particular emperors.
Five Roman Sites to Explore Along Dunav Ultra
1. Ratiaria: The Roman City Near Archar
Near the village of Archar, not far from Vidin, lie the remains of Ratiaria, one of the most important Roman cities along the Lower Danube.
Originally associated with the military presence on the frontier, Ratiaria was granted the status of a Roman colony under Emperor Trajan in the early 2nd century. During Late Antiquity, it became the capital of the province of Dacia Ripensis.
Archaeological excavations have uncovered fortifications, public and residential buildings, and numerous objects offering glimpses into everyday Roman life.
Particularly significant discoveries were made in 2025 and 2026 at the Roman imperial baths, among the largest complexes of their kind excavated in Bulgaria. Archaeologists uncovered monumental chambers, pools and sections of an underground drainage system. The scale of the baths reflects Ratiaria’s importance as an urban and administrative centre.
Along the route: Travelling from Vidin on road II-11, take the right-hand turn just before reaching Archar. A paved road leads approximately 600 metres to the archaeological site. The bath excavations are clearly visible on the left after the turn-off. Admission is free.
2. Oescus: The Forgotten Roman City Near Gigen
Near the village of Gigen, close to where the Iskar River meets the Danube, stand the remains of the ancient city of Ulpia Oescus.
The Fifth Macedonian Legion (Legio V Macedonica) was stationed here during the 1st century AD. Under Emperor Trajan, Oescus became a Roman colony and developed into one of the major urban centres of Lower Moesia.
The archaeological site contains the remains of streets, a forum, temples, public baths and impressive civic buildings. Among its most valuable discoveries are colourful Roman mosaics, some of which are now displayed at the Regional History Museum in Pleven. Even visitors with little interest in archaeology may find the site striking. Ancient streets, columns, friezes and capitals lie scattered across the ruins, almost as though an earthquake had shaken the city apart.
Oescus is also closely connected with the Roman bridge to Sucidava, on the opposite bank in present-day Romania. Inaugurated in AD 328, the bridge was one of the major engineering achievements of the Late Roman Empire. Its foundations remain in the riverbed and can approach the surface when water levels are exceptionally low. That happened in 2026, when parts of the structure became visible just centimetres below the Danube’s surface for the first time in more than 50 years.
Along the route: At the exit from Gigen, take the left turn towards Zagrajden. The archaeological site is approximately 500 metres from the junction, with signs pointing the way. Leave your bicycle in a suitable place and continue about 200 metres on foot to explore the Roman streets and building remains. The site is open and grassy. In summer, watch for snakes among the warm stones and vegetation, and wear closed-toe shoes. Avoid pushing your bicycle through the grass: the sharp seed burrs of puncturevine (Tribulus terrestris) can puncture tyres.
3. Dimum: The Roman Customs Post in Belene
In the town of Belene, directly beside the Danube, lie the remains of Dimum, an ancient Roman fort and customs station.
The fortification served a military purpose but also helped control the movement of people and goods along the river. Its strategic position allowed the Romans to monitor an important stretch of the waterway and regulate trade.
Archaeological excavations have revealed sections of the defensive walls and buildings dating from different periods of the site’s history.
Along the route: Dimum is located within Belene, close to the riverbank, making it an easy stop for cyclists passing through town. Next to the archaeological site is the visitor centre of Persina Nature Park, which is also worth exploring. Its exhibitions introduce the natural environment of the Belene Islands, the Danube wetlands and the distinctive plants and wildlife of the region.
4. Novae: The Roman Legionary Fortress Near Svishtov
Approximately two kilometres east of Svishtov lies Novae, one of the most extensively studied Roman military sites along the Bulgarian Danube.
Established in the 1st century AD, the fortress was associated for centuries with the First Italic Legion (Legio I Italica).
Excavations have uncovered the principia, or military headquarters, legionary baths and a military hospital known as the valetudinarium. The hospital remains offer a particularly interesting insight into Roman military medicine and the organisation of daily life within a legionary fortress.
During Late Antiquity, Novae gradually developed into a fortified town with Christian churches and a civilian population.
Along the route: Novae stands directly beside the road from Svishtov towards Ruse. Approximately 400 metres before the archaeological site, on the left side of the road, is a visitor centre. Here you can see replicas of Roman armour and learn more about the organisation and everyday life of the legionary fortress.
5. Durostorum: Discovering Roman Silistra
Modern-day Silistra preserves the remains of Durostorum, an important Roman military and urban centre on the Lower Danube.
The Eleventh Claudian Legion (Legio XI Claudia) was stationed here in the early 2nd century AD. Its presence encouraged the development of fortifications, roads, workshops and civilian settlements.
Over the following centuries, Durostorum grew into a significant regional centre. Its history continued through Late Antiquity and the Middle Ages, when the town became known as Drastar.
Along the route: Roman remains can be found at several locations throughout Silistra, including among modern buildings and public spaces. Sections of the ancient fortifications can be explored on foot or by bicycle in the city centre and near the Danube. Many archaeological discoveries are preserved at the Archaeological Museum in Silistra, which offers an excellent introduction to Durostorum’s heritage. Highlights include Roman helmets, sculptures, jewellery, architectural fragments and a sundial depicting Orpheus. The museum also displays a replica of a 3rd-century Roman chariot.
More Places to Explore Roman History Along the Danube
Riben: Ad Putea
Near the village of Riben, in the Pleven region, lie the remains of Ad Putea, an ancient Roman settlement and road station. The site was connected to the Roman road between Oescus and Philippopolis (modern-day Plovdiv). The visitor centre explores the history of the settlement and the road network that linked the Danube frontier with the interior of the Balkan Peninsula. Visiting Ad Putea requires a detour from the main Dunav Ultra route.
Official website: Ad Putea – Riben
Ruse: Sexaginta Prista
In central Ruse, visitors can explore the remains of the Roman fortress of Sexaginta Prista. Its name is traditionally translated as the “Port of Sixty Ships”, reflecting the importance of river transport in the Roman period. The archaeological site contains sections of fortifications and military buildings. Although the surviving remains are relatively limited, a guided visit is highly recommended. The explanations provided by museum specialists help bring the fortress to life and reveal its role within the Danube Limes.
Official website: Regional History Museum – Ruse
Pleven: Regional History Museum
The archaeological collection at the Regional History Museum in Pleven includes discoveries from Ulpia Oescus and other ancient sites in the region. Among its most valuable exhibits are Roman mosaics, sculptures and architectural fragments. A particular highlight is a mosaic depicting a scene from the ancient comedy The Achaeans, discovered during excavations at Oescus. The museum lies outside the main Dunav Ultra route but is well worth visiting on a separate trip through the region.
Official website: Regional History Museum – Pleven
Sofia: National Archaeological Museum
The National Archaeological Museum in Sofia offers a broader perspective on the Roman provinces in present-day Bulgaria, exploring urban culture, religion and everyday life in antiquity. Its collections include sculptures, inscriptions, architectural fragments and artefacts from Roman and Late Antique settlements. Among the notable exhibits is the Bukyovtsi Silver Treasure, discovered near present-day Mizia and featured among the 100 Dunav Ultra Highlights. The museum is an excellent place to explore the historical background before setting off on a Danube cycling journey or to deepen your understanding of the region after completing the route.
Official website: National Archaeological Institute with Museum
Events: Eagle on the Danube International Festival
The Eagle on the Danube International Festival of Ancient Heritage is Bulgaria’s largest Roman historical reenactment event. Held annually, it brings together participants from Bulgaria and other European countries. The programme features reenactments of Roman military campaigns and battles, gladiatorial combat, demonstrations of ancient crafts, traditional clothing, weapons and everyday life. Visitors can explore reconstructed Roman military camps and take part in themed workshops and activities. For travellers interested in Roman history and archaeology, the festival provides an excellent reason to plan a separate visit to the region.
Official website: Eagle on the Danube Festival
Cycling in the Footsteps of Roman Legions
Between Archar and Silistra, the Dunav Ultra route crosses landscapes that formed part of the Roman frontier nearly 2,000 years ago. The remains of ancient cities, fortresses and roads reveal the scale of Rome’s military presence and the importance of the Danube as a corridor for transport and trade.
On some sections of the route, you may cycle just metres from an ancient road station or follow a corridor used since Roman times without noticing any visible traces. Much of the original infrastructure has disappeared or remains buried underground. Yet archaeological research, historical records and surviving structures have helped identify the locations of numerous Roman sites.
Exploring this heritage does not mean visiting every archaeological site on a single journey. Some deserve several hours of wandering, while others make rewarding short stops along the way.
Travelling by bicycle also offers a chance to appreciate the landscapes between the ancient settlements. The riverbanks, open plains and natural passages help explain why the Romans chose these particular locations for their fortresses, roads and trading centres.
Below is an extended list of Roman sites along or near the Dunav Ultra route, arranged from west to east. Some remains are visible and accessible to visitors, while others are buried or difficult to identify on the ground. Together, they reveal the remarkable extent of the Roman frontier along the Danube.
Modern location · Ancient name · Type of site
Vrav, Dorticum, Roman fort
Florentin, Florentiana, Roman fort and Late Antique fortres
Koshava, Ad Malum Roman, fortified outpost
Vidin, Bononia, Late Roman fortress and fortified town
Archar, Ratiaria, Roman city, colony and military centre
Orsoya, Remetodia, Roman fortified outpost
Lom, Almus, Roman fort and port settlement
Stanevo, Pomodiana, Roman fortification, burgus and Late Antique fortress
Gorni Tsibar, Cebrus, Roman fortified outpost
Harlets, Augustae, Roman fort and Late Antique fortified centre
Leskovets, Variana, Roman fortress and road station
Dolni Vadin, Valeriana / Pedonianis, Roman and Late Antique fortification
Baykal, Palatolium, Late Antique fortress
Gigen, Ulpia Oescus, Legionary fortress and Roman city
Gulyantsi, Utus, Roman road station and fortified outpost
Cherkovitsa, Lucernaria, Late Antique watchtower
Nikopol (Nikopol Fortress), Securisca, Late Roman fortification and fortified settlement
Belene, Dimum, Roman fort
Svishtov, Novae, Legionary fortress and Late Antique town
Krivina, Iatrus, Late Roman fort
Batin, Scaidava, Roman and Late Antique fortification
Mechka (Stalpishte area), Trimammium, Roman fort
Ruse, Sexaginta Prista, Roman military camp and fort
Marten, Tegra / Tigra, Roman fortified outpost
Ryahovo, Appiaria, Roman fort and Late Antique fortress
Tutrakan, Transmarisca, Roman fort and Late Antique fortress
Malak, Preslavets, Candidiana Roman and Late Antique fortification
Vetren, Tegulicium, Roman road station, later developed into a fort
Silistra Durostorum, Legionary, fortress and Roman city
