Castrum Apulum: the Roman legionary fortress beneath Alba Iulia
Castrum Apulum was the Roman legionary fortress at the heart of today’s Alba Iulia in Transylvania, Romania. Built after Trajan’s conquest of Dacia, it housed the Legio XIII Gemina and grew into the largest urban centre of the province. Part of it is reconstructed and can be seen on the Three Fortresses Route.
Alba Iulia hides three fortresses on one spot, and the oldest is Roman: Apulum, home to a whole legion, was nicknamed the “city of gold” under Emperor Trebonianus Gallus.
The history of Castrum Apulum
Apulum began as a military base. When Trajan finished the conquest of Dacia in 106, he moved the Legio XIII Gemina, until then stationed at Vindobona, today Vienna, to the new province. It was camped on the banks of the Mureș, in a land rich in gold and on the route by which the metal travelled to Rome, and guarding both was part of its task. The fortress was a square of about 400 by 400 metres, and beside it the civilian quarters, the so-called canabae legionis, spread over roughly 500 by 700 metres. The name came from Apoulon, a Dacian hill fortress on Piatra Craivii that the Romans destroyed in the early 2nd century.
In the time of Hadrian and Antoninus Pius the fortress was rebuilt in stone. Around it a remarkable urban landscape took shape. Under Marcus Aurelius one settlement became a municipium, and under Commodus it was raised to the rank of colonia Aurelia Apulensis. Septimius Severus later created a second one, the municipium Septimium Apulense. Apulum became the seat of the governor of Dacia, and after 170 a praetorium was built just east of the legionary fortress. The province of Dacia Apulensis was named after the town. With temples, baths and a governor’s palace, the whole complex covered an urban area of about 300 hectares, the largest concentration of population in Roman Dacia. Its wealth, fed by trade and by the nearby gold mines of Alburnus Maior, earned it the name Chrysopolis, the city of gold, in the time of Trebonianus Gallus.
The legion left in 271, when Rome gave up the northern part of Dacia. Yet the place never emptied. Stone from the Roman camp was reused when the medieval fortress of Bălgrad was built in the 16th and 17th centuries, and in the 18th century the Vauban-style Alba Carolina fortress was raised on the same ground, each new one enclosing the older. Renaissance scholars were already copying Roman inscriptions here, and Giuseppe Ariosti, the architect of the Alba Carolina citadel, left a manuscript on them.
Systematic digging began at the end of 1888, when the self-taught archaeologist Béla Cserni started work in the former governor’s palace and continued until 1915. In 2011 new finds appeared, among them a marble relief of a soldier and an altar to the goddess Nemesis, and archaeologists identified the praetorium, the Via Principalis and the foundations of soldiers’ barracks. The castrum is today partly reconstructed and belongs to a visitor route through three fortresses, and since 2024 Apulum is part of the UNESCO-listed Dacian Limes.
Curiosities about Castrum Apulum
- Apulum’s wealth, born of trade and nearby gold mines, earned it the nickname Chrysopolis, the “city of gold”, under Emperor Trebonianus Gallus.
- In 2011 archaeologists found a marble relief of a bearded soldier with the words SECUNDA RUDIS, “second wooden sword”, a mark of promotion linked to gladiators who became officers.
- An altar to Nemesis, the Roman goddess of vengeance, was found near the Roman Catholic church, which led researchers to suspect a sacred building inside the castrum.
- Three fortresses stand on this one spot: the Roman castrum of 106, the medieval Bălgrad fortress of the 16th–17th centuries and the 18th-century Alba Carolina, each enclosing the one before.
- The first great field archaeologist here, Béla Cserni, taught himself the craft, dug from 1888 to 1915 and died in 1916.
- The name Apulum comes from Apoulon, a Dacian hill fortress mentioned by Ptolemy, which stood on Piatra Craivii, a mountain 1,078 m high.
Tours near Castrum Apulum
Experiences in the area that you can book online with Viator:
Visiting Castrum Apulum: what to see
- The castrum is part of the Three Fortresses Route in Alba Iulia, which lets you travel through two thousand years on one site: Roman Apulum, medieval Bălgrad and the Alba Carolina fortress.
- A partly reconstructed Roman gate, the Porta Principalis Dextra, can be seen in the fortress area, and the changing of the guard is seen through a Roman castrum gate.
- Near gate IV of the Alba Carolina fortress, archaeologists made the 2011 discoveries, and traces of the praetorium and the Via Principalis have been identified.
- Alba Iulia Fortress, on the same ground, is the natural companion; Câlnic Fortress is about 21 km away and Căpâlna Fortress about 27 km.
- Check the current opening hours and any access rules before you go.
Opening hours, access and conditions can change. Check before you go.
Map: where Castrum Apulum is
Map: © OpenStreetMap contributors
Photos of Castrum Apulum
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Questions
What is Castrum Apulum?
It was the Roman legionary fortress of Apulum in today’s Alba Iulia, home to the Legio XIII Gemina from 106 until the legion left in 271. A large city grew around it.
Where is Castrum Apulum?
In the town of Alba Iulia in Transylvania, beside the Mureș river, on the ground now occupied by the later fortress of Alba Carolina.
Which legion was based at Apulum?
The Legio XIII Gemina, moved here from Vindobona after Trajan’s conquest of Dacia, with the task of guarding the gold-bearing land and the road that carried the gold to Rome.
Why was Apulum called the city of gold?
It grew rich through trade and its closeness to the gold mines of Alburnus Maior, and in the time of Emperor Trebonianus Gallus it was called Chrysopolis, the city of gold.
Is Apulum a UNESCO site?
Yes. In 2024 it was inscribed together with other monuments of the Dacian Limes.
What else can you see in Alba Iulia?
The Three Fortresses Route links the Roman castrum with the medieval Bălgrad fortress and the Vauban-style Alba Carolina citadel, all on the same ground.
Also nearby
Alba Iulia Fortress
Alba Iulia · star-shaped Vauban citadel on Roman foundations
150 m away
Câlnic Fortress
Alba · double-walled Saxon refuge with a museum keep
21 km away
Căpâlna Fortress
Alba · Dacian hill fort burned by the Romans in 106 AD
27 km away
Sarmizegetusa Regia
Hunedoara · Dacian capital with sanctuaries, UNESCO site
54 km away