Clan Rising
Duborg Castle today

Germany · Demolished

Duborg Castle

Duburg

Duborg Castle (Duborg/Duburg, also historically called Marienburg) was a fortified hilltop castle in Flensburg, Schleswig, erected in the early 15th century and used as a Danish royal residence in the early modern period. It commanded the harbour and served defensive and residential roles until demolition began in the 18th century and the last remnants were removed around 1900.

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Photograph via Wikimedia Commons

First raised

1411

Its prime

1646

Today

Demolished

As it stood in 1646

What Duborg Castle looked like in its prime.

Perched on a low promontory above Flensburg harbour, the castle forms a multi-winged stone complex encircled by continuous curtain walls punctuated by round and square towers. The roofs are steeply pitched with red tile and numerous smaller turrets and chimneys break the skyline; a tall, slender spire rises from within the compound. Sea-facing bastions and embrasured gun-positions line the harbour side; a broad inner courtyard lies at the complex centre, the masonry a mix of light grey stone and brick. The castle is complete and occupied.

Its story

The story of Duborg Castle.

Duborg Castle was erected by Margaret I of Denmark and Eric of Pomerania on a hill commanding Flensburg's harbour; it took five years to build, with work continuing on parts of the fortifications after Margaret's death in 1412.

When Christian I of Denmark became Duke of Holstein in 1460 he inherited the castle, which remained with the Danish kings after the partitions of Schleswig. In the 16th and 17th centuries Duborg served as the centre of Danish royal power in Schleswig and concurrently as a residence of Danish monarchs. It ceased to be a royal residence in 1703, demolition began from 1719, and the last remnants were removed around 1900.

Step inside

8 places to explore in 1646.

The record describes 8 distinct spots at Duborg Castle, including 2 interiors: great hall, royal bedchamber (birth chamber of christian v). Create your own photoreal reconstruction and explore every one, more scenes means more rooms, more angles, and more of the place to stand in.

Harbour approach looking up to the castleAscending path to the castleMain gate and gatehouseCurtain walk and battlementsSea-facing bastion and gun platformCentral inner courtyardGreat HallRoyal bedchamber (birth chamber of Christian V)

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The artist rebuilds it as it stood in 1646, a photoreal reconstruction that belongs to you alone. Pay with coins, no subscription needed.

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Nearby

Landmarks within reach of Duborg Castle.

Hedeby, GermanyAncient siteHedeby35 km awayDanevirke, GermanyAncient siteDanevirke35 km away

Questions about Duborg Castle

What is the history of Duborg Castle?

Duborg Castle began as a fortified hilltop castle in the early 15th century to control Flensburg and defend its harbour against attacks from the west. Built by Margaret I of Denmark and Eric of Pomerania, it later became a centre of Danish royal power in Schleswig and a residence for Danish monarchs. It ceased to be a royal residence in 1703, and demolition began in 1719.

What is inside Duborg Castle?

Duborg Castle had a Great Hall and a Royal bedchamber, identified as the birth chamber of Christian V. Its central inner courtyard was enclosed by the castle’s wings and curtain walls. The documented spaces also include the curtain walk and battlements, although the castle itself has been demolished.

Why was Duborg Castle built, and what was it used for?

Duborg Castle was built as a defensive stronghold commanding Flensburg harbour and protecting against the Holsteinians. Its harbour position allowed the castle to defend the water and its location to control the town. It later served both as the centre of Danish royal power in Schleswig and as a residence for Danish monarchs.

Where is Duborg Castle?

Duborg Castle was in Flensburg, Schleswig, on a hill above the harbour. It stood on the Marienberg, a hill on the west bank of Flensburg. The castle’s position commanded the harbour and formed part of the town’s defensive system.

When was Duborg Castle built?

Duborg Castle was built in the early 15th century, with its first construction dated to 1411. The work took five years, and parts of the fortifications continued after Margaret I’s death in 1412. The castle therefore belongs to the 15th century, rather than being a later early-modern construction.

Was Duborg Castle ever attacked or besieged?

Duborg Castle was besieged and attacked several times. In 1422, a northern assault by Count Henry IV of Holstein failed, and a Hanseatic and Schauenburg force also failed to take it after a two-week siege in 1427. In 1431, the castle resisted until 1 September but finally capitulated after a combined sea and land blockade caused it to surrender through starvation.

What did Duborg Castle look like in its prime?

At its height, Duborg Castle was a large, multi-winged stone complex enclosed by continuous curtain walls with round and square towers. It had steep red-tiled roofs, smaller turrets, chimneys and a tall slender spire. Sea-facing bastions and gun positions defended the harbour side, while a broad inner courtyard occupied the centre.

Is Duborg Castle still standing, or is it a ruin?

Duborg Castle is no longer standing; it was demolished. Demolition began in 1719, and the last remnants were removed around 1900. A south-eastern corner of the ruins survived into the 19th century, but it was removed in 1898–1900 during the urban development of the district.

Who built Duborg Castle?

Duborg Castle was commissioned and built by Margaret I of Denmark and Eric of Pomerania. Construction began under Margaret, and continued under Eric after her death in 1412. Jens Due may have been responsible as builder, but the documented account does not identify a separate architect.

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