Sucidava · Olt County, Romania · the Danube
Constantine the Great's bridge at Sucidava: 2,437 metres across the Danube, from AD 328
Choose a pace and walk its whole length — 2,437 metres, a mile and a half — on a to-scale drawing, while Trajan's bridge, drawn underneath, ends at less than half.
Sucidava fortress stands by Corabia, in Olt County on the Danube.
1,698 years have passed since the bridge was opened, in July 328.
The distance is computed in the browser; the reader's location never leaves the device.
The bridge on the Danube, 328–2026
From the opening to the drones: six stops along the water.
5 July 328
The bridge whole
On 5 July 328 Constantine the Great is at Oescus, signing a law. The bridge between Oescus and Sucidava — 2,437 metres of timber and stone — joins the two banks. Its northern end starts at the south-west corner of the fortress.
under Valens, 367–369
The bridge falls out of use
Around 367–369 the bridge was very probably already unusable: it is simply missing from the record of Valens's wars against the Goths. The emperor crosses the Danube on planks laid over boats, near Daphne.
July 1869
One pier on the fairway
In July 1869 Cezar Bolliac records a stone pier on the navigable channel, close to the Romanian bank. Four years later he uncovers the northern portal. Felix Kanitz learns from the locals: at low water, the piers rise out of the Danube.
October 1933
Three piers on the riverbed
Soundings by the Hydraulic Service plot three masonry piers on the Danube bed: 165 metres between the northern and middle piers, 130 between the middle and southern. Measured at the base: 25–26 by 19 metres.
19 May 2017
27 traces over 820 metres
A multibeam sonar finds 27 possible traces of the bridge, strung over 820 metres about 30 metres apart. In 2022 magnetometry adds seven possible piers on the floodplain, on the same line.
August 2026
The Danube gives it back
Drought lowers the Danube and the foundations surface near Gigen. The Pleven museum team photographs them by drone and plots their line. Next: the walk, at your pace.
The walk: 2,437 metres at your pace
The drawing is to scale: one millimetre on screen means the same number of metres, portal to portal. Choose a pace, press Walk, and walk the whole length. Underfoot, the tally divides stone from timber; below, Trajan's bridge ends at less than half.
2,437 metres is about 23 football pitches end to end (105 metres each).
Metre 0 of 2,437.
Your walking time this far: 0 seconds.
Underfoot: the northern portal, stone masonry.
Stone underfoot: 0 m of 0 m walked (0%).
The whole bridge, at your pace: 29 min 15 s.
Here, at 1,135 metres, Trajan's bridge ends.
Crossing times, computed: 4 km per hour — 36:33; 5 km per hour — 29:15; 6 km per hour — 24:22.
The model's tally, printed: 71.0 m of stone in 2,437 (2.9%).
- stone
- timber
- water
- lost
- Trajan's bridge, same scale
What the drawing shows
A lengthwise section of the bridge, to scale: the northern portal, seven possible pier traces on the floodplain, the northern arm, three masonry piers in the main arm, 1,137 metres of water at the 1933 soundings, the southern bank with no portal. Below, Trajan's bridge (1,135 metres) ends at less than half.
1873
The northern portal
The only end ever studied: a stone platform 14.50 by 7.00 metres, limestone facing, a spur that broke the waves. Estimated original height: 21 metres. The foundation is still visible, about 140 metres from the south-west corner of the fortress.
2022
Seven possible piers on the floodplain
The October 2022 magnetometry finds seven oval anomalies, about 10 metres across, some 30 metres apart, on the bridge line. The magnetic trace fades towards the Danube, a sign the piers here survive worse; separately, the authors presume they were timber.
today a brook
The northern arm
In antiquity the Danube ran in two arms; the small northern one is gone — barely a hint remains in the Bozahuz brook. On 19 May 2017, near KM 634+500, the main arm measured 1,240 metres, about 100 more than in the 1933 soundings. In the floods of 2006 the river briefly recovered a course much like its ancient one.
1933
The northern pier
One of three masonry piers in the navigable arm: 25–26 by 19 metres at the base, with spurs upstream and down.
1933
The middle pier
165 metres from the northern pier; 130 metres stand between it and the southern pier.
1933
The southern pier
The southernmost of the three piers plotted in October 1933.
1836–1898
The southern portal: lost
Recorded in 1836 near the Iskar mouth, guessed in 1898 from Roman bricks. Today it cannot be found: a great interwar earth dyke stands in its place.
What was written, and what never was
The bridge appears in few ancient lines. More eloquent is its silence: twice, when the Danube had to be crossed, the bridge is nowhere.
- 5 July 328
A law signed at Oescus
Dat. III non. Jul. Yscoi.
The emperor signs a law at Oescus — issued on the third day before the Nones of July, 5 July — in the consulship of Ianuarinus and Iustus. His presence there, at the bridge's southern foot, belongs with the opening of the work.
- fourth century
The earliest mention
Pons per Danuvium ductus; castra castellaque pluribus locis commode posita.
Aurelius Victor, On the Caesars: “A bridge was stretched across the Danube; forts and fortlets were raised in many fitting places.”
- seventh–eleventh centuries
The chroniclers remember stone
…made a stone bridge over it…
The Chronicon Paschale, Theophanes and Kedrenos all record a stone bridge over the Danube: Constantine crossed the river and made a stone bridge over it. After Tudor, only the ends and the three Danube piers are certainly masonry; the rest was probably timber alone.
- spring 367
Valens crosses on boats
Ammianus Marcellinus: the emperor camps near Daphne and crosses the river on planks laid over boats. Constantine's bridge, not forty years after its opening, was very probably already unusable.
- 376
The silence of 376
When the Goths cross the Danube ahead of the Huns — in boats, on rafts and hollowed tree-trunks, many drowning — Ammianus never mentions the bridge at all. Nor does Procopius of Caesarea, two centuries later.
- 1860–1879
The piers rise from the water
…bei niedrigem Wasser die Pfeiler der alten Steinbrücke in regelmässigen Abständen sichtbar werden und bei kleinstem Wasserstande sogar 1-2 Meter über dem Donauspiegel emporragen.
Felix Kanitz, after locals and pilots: at low water the piers of the old stone bridge show at regular intervals, and at the lowest water they rise 1–2 metres above the Danube.
- 1878
Why a “brass bridge”
…o scoabă de aramă ca de 3 siuhi de lungă (adică de 3 picioare = 90 cm), în patru muchii, groasă ca un fier de plug…
People on both banks call it the brass bridge, holding its feet were cast from metal. The kernel of truth, printed by Odobescu in 1878 after the notes of surveyor Alexandru Popovici: a bronze clamp about 90 centimetres long, fished from the Danube with a spear.
- 328
The Rome medallion
The opening was struck on a gold (?) medallion, now lost; two bronze copies survive, in Vienna and Paris. On the reverse, from published descriptions: a stone bridge of three arches with a watchtower at one end — elements copied after an ancient original.
What is left on each bank
The two ends had different fates: the northern one has been studied for over 150 years, the southern one was lost under a dyke.
The northern bank: Celei
- The northern portal, uncovered by Bolliac in 1873 and dug by Tocilescu and Polonic in the summer of 1898, and by Toropu in 1968.
- Beside it, the 2002–2003 digs found masonry attributed to a timber footbridge towards the fortress gate: 140 metres instead of a 487-metre detour.
- At 1,479 metres from the portal — one Roman mile — stood the milestone of the year 328, naming Constantine and the two Caesars.
- The road to Romula, more than 45 kilometres north, is visible on the ground for 17.5 kilometres.
The southern bank: Gigen
- The southern portal, recorded in 1836 and guessed in 1898, can no longer be found: the earth dyke between the Iskar and the Trinca covers it.
- A 1905 plan shows the raised road through the floodplain, over 3.5 kilometres, between the bridge and the north gate of Oescus.
- In August 2026 low water exposed foundations near Gigen, photographed by drone by the Pleven museum.
Sucidava fortress — about 1.4 hectares, a garrison of the legion V Macedonica, one of Rome's standing legions — was rebuilt by Justinian after the Hunnic destruction and held until the end of the sixth century. The bridge, though, is nowhere attested as rebuilt.
The way: what can be seen
The bridge can no longer be crossed, but its northern end can be stood upon; the southern one is nowhere to be found.
- The northern portal foundation, about 140 metres from the south-west corner of Sucidava fortress.
- The Danube bank at low water: when the river falls far, the piers surface — so the pilots saw them in 1860–1879, and the drone in August 2026.
- Oescus across the river, near Gigen: the city from which the 3.5-kilometre road set out for the bridge.
From you: Sucidava km · Oescus (Gigen) km.
Sources and method
- The length is given as a range, 2,434–2,437 metres, with both sources shown: Tudor (via Opriș et al., 2022) and Gherghe–Amon (2007).
- Pier positions in the drawing are approximate, placed from the published distances (165 and 130 metres, the 30-metre rhythm) — not a survey.
- The bridge axis in the 3D scene starts at the northern portal and reaches the southern bank at 2,437 metres, on a bearing searched in the terrain model; it is a working axis, not a measured one.
- The water level is a terrain-model reading, held constant through the scene; no source gives the level of the year 328.
- The renderings from Latin and German stand beside the original texts; from the chroniclers, the page gives renderings after Opriș et al. 2022.
- The medallion is described from the published literature; the page links to the Vienna museum record.
- What is not known: who designed it (the Theophilus Patricius hypothesis is a guess), how and exactly when it was decommissioned, where the southern portal lies.
- The stone tally counts both portals (the lost southern one assumed alike: 7 metres) and the three 19-metre piers; the rest is the timber hypothesis.
The bridge
- I. C. Opriș, A. D. Ionescu, A. C. Surleanu, A. E. Stănișteanu, M. Dragomir, C. G. Simion, A. I. Cercel, V. Speriatu, C. Dobrinescu, A. Șerbănescu, V. Călina, “Pons per Danuvium ductus. Date noi despre podul lui Constantin cel Mare dintre Oescus și Sucidava”, Cercetări Arheologice 29.2 (2022), 631–664. doi.org
- P. Gherghe, L. Amon, “Noi date în legătură cu podul lui Constantin cel Mare de la Sucidava”, Pontica 40 (2007), 359–369. revistapontica
- Romanian National Archaeological Record, file 125551.08: “Podul roman de la Corabia – Podul lui Constantin”. ran.cimec.ro
- D. Tudor, Podurile romane de la Dunărea de Jos (1971) and Sucidava (1974), cited via Opriș et al. 2022.
Ancient sources
- Sextus Aurelius Victor, Liber de Caesaribus 41.18 (Latin text). thelatinlibrary.com
- Ammianus Marcellinus, Res Gestae XXVII.5 and XXXI.4 (Rolfe transl.). LacusCurtius
- The 328 medallion: bronze copies at the Kunsthistorisches Museum, Vienna (Münzkabinett, RÖ 32345) and the Cabinet des Médailles, Paris (catalogue.bnf.fr). khm.at
Summer 2026
- Reuters, 6 August 2026: low Danube water exposes the bridge near Gigen. reuters.com
- Basilica.ro, 12 August 2026: the Pleven museum team surveys the foundations on 4 August. basilica.ro
Data and map
- 3D relief: Copernicus DEM GLO-30, © European Space Agency. Coordinates: Nominatim (© OpenStreetMap contributors, ODbL). Photos: Wikimedia Commons, licences with each image. 3D rendering: the Three library from threejs.org.
The sibling bridge, at Drobeta: Trajan’s Bridge. A place drowned: Ada Kaleh. A plan on the Danube: The Danube Tower.