Develtos, the Roman Veterans' Colony and Border Town near Burgas
Develtos, also known as Deultum, was an ancient city by the Mandrensko lake, near the village of Debelt west of Burgas. It began as a Thracian settlement, became a Roman colony for veterans, and later served as a bishopric and a frontier post between Byzantium and Bulgaria. Excavations since the 1980s and a museum opened in 2016 reveal its layers.
A town founded for retired legionaries ended up on the Byzantine-Bulgarian frontier, where a pope's envoys were kept waiting for forty days, and where Bulgaria's first Christian ruler may have been baptised.
The history of Develtos
The area by the lake holds traces of settlement from the Late Bronze Age, followed by a Thracian settlement whose name, Debelton, is understood to mean the area of two swamps. Attic pottery of the first half of the fourth century BCE and later Hellenistic finds show that it had trading links. In the 70s CE, under Emperor Vespasian, the Romans founded here the colony Colonia Flavia Pacis Deultensium for veterans of the VIII Augusta legion. It grew into the second most important city of the province of Thrace and lay at the meeting of major roads. Temples of Asclepius and Cybele stood in the city, large baths were built and rebuilt over the centuries, and from Caracalla to Philip the Arab the town minted its own coins.
Later centuries were rougher. Barbarian raids damaged the city in the second century, Goths sacked it in the third, and in the summer of 377 an Eastern Roman army was beaten outside its walls and the city was plundered again. It was rebuilt on a smaller scale, with new walls in the second half of the fifth century, which Slavs and Avars destroyed at the end of the sixth. Bishops of Develtos are recorded from the second century onwards, and one of them, Saint George, was deported after the city fell to Khan Krum in 812.
After the treaty of 716 Develtos lay on the border with Bulgaria and became a significant defensive post. Krum besieged it in May 812; it surrendered in June and was destroyed, and its people were moved away, but it was later resettled with Bulgarians. A treaty in 816 returned it to Byzantium and a great fortified earthwork was built north-west of it to mark the frontier. In 866 an embassy of Pope Nicholas I to the emperor was stopped at Develtos and forced to wait forty days before turning away to Pliska. Boris I, the first Christian ruler of Bulgaria, may have been baptised here around 864, and his lead seals have been found on the site.
Tsar Simeon I received the city under the treaty of 896, and it was named as the place where the annual tribute to the Bulgarians was to be delivered. In 913 he marched on Constantinople by way of Develtos, and in 927 the city passed back to Byzantium. In 1203 Emperor Alexios III Angelos took temporary refuge here after fleeing Constantinople. The Second Bulgarian Empire took the town after 1205, but the Byzantines recovered it in 1263.
From the thirteenth century the lagoon silted up and rising waters changed the shoreline, the harbour shifted east towards today's Burgas, and the town declined. It was emptied in the fourteenth century, whether through Turkish attacks or the silting, and after that it no longer appears in the written sources. The Ottomans conquered the region in 1396.
Curious facts about Develtos
- The Thracian name Debelton is understood to mean “two-swamp area”, which still suits the terrain by the lake.
- In 866 an embassy of Pope Nicholas I had to wait forty days at Develtos before giving up and heading for Pliska.
- Three lead seals of Boris I were found here, reading “Christ help Michael, archon of Bulgaria”, which led scholars to suggest that Bulgaria's ruler was baptised here.
- In 2020 a sarcophagus of the second or third century with a Greek inscription proved that Develtos was a port town.
- An amulet from the late second to early third century, found in 2024, contains the first known reference to Christ in the region.
- Within about three square kilometres by the lake, more than twenty-five sites have been recorded, from the Late Bronze Age to the late Middle Ages.
Tours near Develtos
Experiences in the area that you can book online with Viator:
Visiting Develtos: what to expect
- The remains lie in open fields outside the village of Debelt, so wear sturdy shoes and expect little shade.
- Excavations have uncovered the eastern gate with niches for statues, part of the main street, baths and a temple of the imperial cult.
- A museum dedicated to the site opened next to it in 2016; its exhibits include a bronze head of Septimius Severus. Check the current opening hours before you go.
- On the hill east of the medieval fort lies a rock-cut necropolis of the second and third centuries, and a ninth-century church was explored at a spot called Kostadin cheshma.
- Nearby places on this site include Beglik Tash, about 41 km away, and Markeli, about 42 km away.
Opening hours, access and conditions can change. Check before you go.
Map: where Develtos is
Photos of Develtos
Questions
What is Develtos?
Develtos, or Deultum, was an ancient city and bishopric in Thrace. It began as a Thracian settlement, became a Roman veterans' colony and later a frontier town between Byzantium and Bulgaria.
Where is Develtos and how far is it from Burgas?
It lies by the village of Debelt, west of Burgas, on the western shore of Lake Mandrensko. The sources give differing distances, so check a map before you go.
Why is Develtos important to Bulgarian history?
In the early Middle Ages it stood on the Byzantine-Bulgarian border. Three lead seals of Boris I found there led scholars to suggest that Bulgaria's ruler was baptised in this area.
What has been found at Develtos?
Excavations have uncovered baths, a temple of the imperial cult, an eastern gate, fortifications, a rock-cut necropolis and a medieval church. Finds include lead seals and a bronze head of Septimius Severus.
Is there a museum at Develtos?
Yes, a museum dedicated to the site opened beside the ruins in 2016. Check the current opening hours before you visit.
What else is worth seeing near Develtos?
Beglik Tash is about 41 km away and Markeli about 42 km. The Church of Christ Pantocrator and Mesembria are about 48 km away.
Also nearby
Beglik Tash
Primorsko · megalithic sun sanctuary above the Black Sea
41 km away
Markeli
Karnobat · border stronghold of two medieval empires
42 km away
Church of Christ Pantocrator
Nesebar · medieval church with lavish patterned walls
48 km away
Mesembria
Nessebar · Thracian town, Greek colony and Roman port
48 km away