Museum of Roman City Diocletianopolis in Bulgaria’s Hisarya Wins Taxation Lawsuit
Today’s spa resort town of Hisarya in Central South Bulgaria, Plovdiv District, is the successor of a prehistoric settlement, an Ancient Thracian town, an Ancient Roman, Early Byzantine, and medieval Bulgarian city called Augusta and Diocletianopolis.
The Roman Era city from the Antiquity and Late Antiquity was first called Augusta, and was later renamed Diocletianopolis after Roman Emperor Diocletian (r. 284 – 305 AD). Today’s name of the Bulgarian town of Hisarya stems from the Turkish word “hisar”, a remnant from the Ottoman period, meaning “fortress”.
Augusta / Diocletianopolis / Hisarya has been a well-known spa resort since the Antiquity thanks to its healing mineral water springs and its mild climate at the foot of the Sredna Gora Mountain.
A prehistoric settlement existed at the site in the 5th – 4th millennium BC.
An Ancient Thracian town which succeeded it was part of the Odrysian Kingdom, the largest Ancient Thracian state, which existed in the 5th century BC – 1st century AD. The Thracian town in question was located very close to the large Ancient Thracian religious and burial facilities at the town of Starosel, including the Starosel burial mound / tomb.
After all of Ancient Thrace south of the Danube River was conquered by the Roman Empire in 46 AD, the Romans expanded the Thracian settlement at Hisarya’s mineral springs.
The town at first known as Augusta in the Roman Era, later the city of Diocletianopolis, was located on a tall terrace between a river and a gully which boosted its natural defenses.
The first major barbarian invasion of the Balkan provinces of the Roman Empire, by the Costoboci ca. 170 AD, did not affect Augusta. Thus, unlike other towns in the Roman province of Thrace (Thracia), which quickly erected fortress walls, Hisarya’s predecessor was left unprotected. This cost the town dearly during the barbarian invasion of the Goths in 250 AD when the Goths plundered it and burned it down.
Augusta was rebuilt by Roman Emperor Diocletian who gave it a city status in 293 AD and renamed it after himself to Diocletianopolis. The restored city received robust fortress walls. Thanks to its mineral springs, in the 3rd century AD, Hisarya’s Roman Era predecessor had become the third largest city in Roman Thrace (Thracia) after Philipopolis (today’s Plovdiv) and Augusta Traiana (today’s Stara Zagora).
The fortress walls of Diocletianopolis first built at the end of the 3rd century AD were revamped and upgraded in the 5th century AD, already at the time of the Eastern Roman Empire (Byzantium).
The best known remnant from the Roman fortress walls in Hisarya is the Southern Gate. Its original height is almost fully preserved (up to a height of 13 meters). It is known as “the camel(s)” because the surviving structure with parts from two merlons resembles two humps on a camel’s back.
The Diocletianopolis Fortress has the shape of a rectangle with sides measuring app. 665 meters by 580 meters. The combined total length of the fortress walls is 2,327 meters. The area of the fortress is more than 33 hectares (app. 82 acres). The northwest wall is 490 meters long, the northeast wall is 654 meters long; the southwest wall is 627 meters long; the southeast wall is 556 meters long.
The fortress walls of Diocletianopolis were built mainly using the opus mixtum Roman building technique alternating stone and brick layers but three other techniques are observed as well.
The walls were between 2.6 and 3 meters thick. The platform on top of the walls was about 2.4 meters wide. The fortress walls have been preserved at a height of between 1.5 and 10.5 meters.
Together with the battlement and the merlons the total height of the fortress walls of Diocletianopolis was probably about 12 – 12.5 meters, which is the same height as the height of the Theodosian Walls of Constantinople or the walls of the Thessaloniki, the second most important city in the Eastern Roman (Byzantine) Empire.
The fortress walls of the Ancient Roman city of Diocletianopolis in the Bulgarian spa resort of Hisarya had a total of 44 fortress towers, including 10 fortress towers on the southwestern wall, 9 on each the southeastern and northeastern walls, 12 on the northwestern wall, which was the most vulnerable of all, and four corner towers.
All but two of the 44 fortress towers were rectangular. Only the northeastern corner tower was octagonal and the southeastern fortress tower had the shape of a fan. Each fortress tower had three floors. The platforms of the walls and those of the towers were connected with small brick staircases, the same way as on the Theodosian Walls of Constantinople.
The four fortress gates of the Roman city of Diocletianopolis bear traces from severe damages from the 5th century AD, probably as a resulrt of the barbarian invasions of the Huns in the Roman Empire.
Diocletianopolis had a total of six posterns (secondary doors) but three of those were walled up in the 5th century AD to increase the safety of the city during sieges.
The northwestern wall of the city had no natural defenses, and in the 5th century a faussebraye (proteichisma), i.e. a defensive wall located outside the main wall of the fortress, was constructed there.
The faussebraye (protechisma) was 503 meters long, 3 meters thick, and 6 meters tall. It was located 10.5 meters before the main wall, and ran parallel to it. Its battlement and merlons were about 1.6 meters tall, bring its total height up to 7.6 meters. This allowed the main wall behind, which was taller, to be used efficiently against the besieging forces. The faussebraye (protechisma) did not have any fortress towers. It did have a gate and a total of seven posterns.
The fortress of Diocletianopolis had a moat which was located 10-15 meters outside the walls. It was not filled with water.
The entire city of Diocletianopolis had a very good drainage and sewerage system, and very good urban planning typical of the Roman cities.
The cardo maximus (the main north-south street) was 11 meters wide, and paved with gravel. The other main street, the decumanus maximus (the main east-west street) was 5 meters wide, and also paved with gravel. The other streets in the city were perpendicular to them and were about 3-4 meters wide.
In addition to its hot mineral springs, Diocletianopolis also had a supply of fresh cold water from the Srendna Gora Mountain through a water pipeline made of bricks and tiles. The pipeline in question was built at the same time as the first fortress walls of the city at the very end of the 3rd century AD.
After the 3rd century AD, the Roman city of Diocletianopolis, today’s spa resort Hisarya in Central South Bulgaria, continued to grow outside its fortress walls.
Alongside the entire southeastern wall and the southern part of the northeastern wall, on the inside, Diocletianopolis had a total of 9 rectangular barrack buildings for the Roman military.
The Roman barracks were built in the middle of the 4th century AD, and were burned down and restored several times.
After its second destruction, the southernmost of the Roman barracks was refashioned into an Early Christian church, a basilica. The other 8 barracks survived until the 7th century AD when they were destroyed for good, seemingly during the barbarian invasions of Slavs and Avars. During the Middle Ages, at the time of the medieval Bulgarian Empire, residential buildings were built on top of the ruins of the Roman barracks.
The Ancient Roman city of Augusta / Diocletianopolis was a well-known spa resort already in Antiquity times thanks to its healing mineral waters. A true testimony to its importance as an ancient spa resort is that fact that it had a total of four thermae (public baths).
Three of its thermae, including the largest public baths in the city, were located inside its fortress, while the fourth were 250 meters each of the fortress wall.
The best researched and best preserved of all Ancient Roman thermae (public baths) in Bulgaria’s Hisarya from the time of Augusta / Diocletianopolis are the large thermae in today’s downtown. Their mineral water supply system is still operational, and their building has been preserved almost up to its roof.
The archaeologists have unearthed there a total of four bathing pools with preserved marble plaster. The central of the four pools had a mineral water spring geyser built into it.
Another from Diocletionapolis’ mineral water thermae was located 30 meters away from the central public baths, near another mineral water spring. Its ruins were discovered back in 1921 but it has not been excavated by archaeologists yet. It was also fed mineral water from a spring outside the fortress walls through an underground water pipeline with clay pipes.
The fact that the ancient spa resort of Diocletianopolis, today’s Bulgarian town of Hisarya, had a fourth thermae complex, outside its fortress walls, 250 meters to the east, is known from a stone inscription found at the respective location, which says that the public baths there were constructed between November 11 and December 31, 308 AD.
The amphitheater of the Ancient Roman city of Diocletianopolis was built 50 meters to the southwest of its central large thermae. It had a peculiar shape because it used the natural slope of the spot.
According to archaeological research, it was a relatively small provincial amphitheater and was constructed after Augusta was upgraded to a city and renamed Diocletianopolis in 293 AD, i.e. at the very of the 3rd century AD.
In the Late Roman and Early Byzantine period, with the adoption of Christianity, that is, in the 4th – 6th century AD, Diocletianopolis became an important religious center. It is believed to have been the center of a bishopric, and contains the ruins of a total of 10 churches from the Early Christian period. Only two of those were inside the fortress walls, the rest were in the outside quarters.
The first traces of Christianity in Dicoletianopolis date back to the beginning of the 4th century, with the first two churches constructed towards the middle of that century.
The homes in the Ancient Roman city that is the predecessor of today’s Bulgarian spa resort of Hisarya were two types – large mansion-type homes with a pool in the middle and additional buildings for the help, storage and trade; and small dwellings for the poorer strata of the population each of which nonetheless had several rooms.
Diocletianopolis in Bulgaria’s Hisarya is one of the best preserved Ancient Roman cities in Europe, whose fortifications and architecture boast a high degree of originality.