Constantine’s Bridge on Danube River at Roman Cities Ulpia Oescus (Gigen, Bulgaria) – Sucidava (Corabia, Romania)

The location of Constantine’s Bridge on the Danube River between today’s Bulgaria and Romania – the largest river bridge in ancient times. It existed for up to 40 years in the 4th century AD. Map: Google Maps

Constantine’s Bridge on the Danube River, the largest river bridge in ancient times, was a bridge in the Roman Empire  which connected the major city of Ulpia Oescus (today’s Gigen in Northern Bulgaria) in the Moesia Superior province with Sucidava (today’s Corabia in Southern Romania) in the Dacia Province.

The first permanent bridge on the Lower Danube was built at the order of Roman Emperor Constantine I the Great (r. 306 – 337 AD). It was one of the most famous Roman bridges of all time.

It was inaugurated on or around July 5, 328 AD, in the presence of Emperor Constantine the Great. It was long nearly 2.5 km (1.55 miles) (more precisely, 2,437 meters); of those, 1137 meters (0.7 miles) spanned the bed of the Danube River.

Constantine’s Bridge was 5.7 meters (18.7 feet) wide, and rose about 10 meters (33 feet) above the waters of the Danube. It had masonry pillars and a wooden superstructure.

The Late Roman bridge was located in the middle between the 634th and the 635th kilometer of the Danube, approximately 5 km (3 miles) north of today’s Bulgarian town of Gigen, and the large Ancient Roman city of Ulpia Oescus.

A well-preserved street in the large Ancient Roman city of Ulpia Oescus whose ruins lie near Gigen, Pleven District, in Northern Bulgaria, as seen in July 2016. Constantine’s Bridge on the Danube connected Ulpia Oescus with Sucidava (in today’s Romania). Ulpia Oescus is some 5 km (3 miles) south of the Danube and the bridge built by Roman Emperor Constantine I the Great. Photo:

Constantine’s Bridge on the Danube is believed to have survived for up to four decades. By 367 AD, the army of Roman Emperor Valens (r. 364 – 378 AD) had to cross the Danube for his campaign against the Goths using a bridge of boats (pontoon bridge) at Constantiana Daphne.

(According to some researchers, the fortress of Constantiana Daphne was located across from the Transmarisca Fortress (in today’s Bulgarian Danube town of Tutrakan); according to others, it was located on the left bank of the Lower Danube where Constantine’s Bridge was, and was opened together with the bridge).

This has led to the assumption that Constantine’s Bridge was no longer in operation by that time. Some hypotheses state that it was destroyed in 355 AD during a barbarian invasion.

There are hypotheses that its wooden superstructure was burned down by the Romans so as to prevent barbarians such as the Goths from using it in their invasions.

Constantine’s Bridge was used by the Romans mostly for the relocation of troops to fight with the barbarians in Dacia, north of the Danube.

It is known that in 332 AD, Constantine the Great’s son and co-emperor, Constantine II (r. 337 – 340 AD) used the bridge to cross the Danube with a large army to fight the Goths, Sarmatians, and Alans north of the river.

In 1726, Italian scholar Luigi Ferdinando Marsigli noted in his work Danubius Pannonico-Mysicus that seven of the pillars of the Constantine’s Bridge were visible.

In 1870, the location where the bridge used to stand was explored and confirmed by Austro-Hungarian geographer and archaeologist Felix Kanitz, and later by Czech-Bulgarian archaeologist Karel Skorpil. Three pillars could still be seen until the 1930s.

Following the demise of Constantine’s Bridge in the 4th century AD, the next bridge across the Lower Danube in the section that has been shared by modern-day Bulgaria and Romania since 1878 has been the “Bridge of Friendship” at Ruse – Giurgiu built at the initiative of Soviet Union dictator Joseph Stalin (as both countries had been part of Soviet Bloc in Eastern Europe at the time). It was completed a year after Stalin’s death, in 1954.

The third Danube Bridge in the Bulgarian – Romanian section has been the New Europe Bridge at Vidin – Calafat completed in 2013 with EU funding.


Relevant Books on

Roman Bridges

The Life and Times of Constantine the Great

Constantine: Roman Emperor, Christian Victor

Ancient Rome: A Complete History of the Rise and Fall of the Roman Empire, Chronicling the Story of the Most Important and Influential Civilization the World Has Ever Known



Support on Patreon

with $1 per Month!

Become a Patron Now!


Make One-time Donation via Paypal!

Your contribution for free journalism is appreciated!


Download the ArchaeologyinBulgaria App for iPhone & iPad!

Follow us on Facebook, Twitter, Google+, Tumblr, Pinterest!

Archaeology in Bulgaria. and Beyond