History - Northern Bornholm and Hammershus

Humans have inhabited the area since the Mesolithic (8.900 to 3.900 B. C.), but it is three distinct historic periods that have left the most visible traces in the landscape: The petroglyphs at Madsebakke and Hammersholm gives a glimpse into the minds of the people of the Bronze Age, Hammershus Castle is a reminder of the medieval power struggles and the many scars in the landscape is a testimony to the rise and fall of the quarrying industry.

About the name Hammershus

The name Hammeren is known from 1539 in the form hammar. This means stony hill or rock.


The bedrock of Northern Bornholm consists of granite created 1.4 billion years ago. Where it isn't covered by a relatively thin layer of soil and sediment the bedrock is visible in the landscape. It have soft, rounded shapes towards the north and north east and is steep towards the west. This is because the bedrock have been worn down by three million years of ice ages that moved large ice masses over the Island from the north east and east. This glacial abrasion is still visible as long lines in the exposed bedrock.

Symbols from the past

Many rocks at Hammersholm and Madsebakke shows petroglyphs - symbols carved into the rock during the Bronze Age. The carvings show numerous cup marks and ships as welll as wheel crosses, horses and footprints. This type of petroglyphs have been found throughout Southern Scandinavia but in Denmark they are mostly known from Bornholm, and the area around Madsebakke and Hammersholm is the largest site.

Ever since the first humans arrived on Bornholm during the end of the last ice age they have left their marks on the island: Practical things like a harpoon made from reindeer antlers, arrowheads made from flint, or a broken clay pot. But in the images from the Bronze Age we get the first glimpse into the thoughts and beliefs of the prehistoric societies.

Cup marks consists of concave depressions and is known as early as the Neolithic. They are associated with fertility cults but are seen at burial sites too.

The Bronze Age society was agrarian and sea faring. The latter may be why we see so many ships depicted. Some scholars believe the depictions of ships to be symbols of political and religious power, but we know nothing for certain.

At Madsebakke the petroglyphs are regularly painted to make them easier to see. In the rest of the area only few are painted regularly, but many of the carvings can be recognized without aid. It is advisable to bring some water to splash on the rock surface as this makes the petroglyphs easier to see.

The Church's castle on Bornholm

Hammershus Castle is Denmarks largest castle ruins. The castle is situated on a lonly rocky knoll 70 meters above sea level. Archaeological surveys indicate that the castle was built around 1300 A.D., probably by Arch Bishop Jens Grand. At that time most of Bornholm was owned by the church, and there was hostilities between church and crown. Hammershus became strategically important in the struggle between church and king that lasted for centuries. The castle changed hands now and then but it always ended up in the churchs possesion.

Ruled by Lübeck

In 1522 the castle shortly returned to the crown but by 1525 it was given to the Hanseatic city of Lübeck for a period of 50 years as security for their support.

Lübeck and The Hanseatic League dominated the Baltic trade and Bornholm and was involved in the booming herring trade. They immediately started expanding the castle, and to that end the population of Bornholm was taxed both materially and in labour, so the new rulers was far from popular. The unrest culminated in a failed rebellion in 1535.

During the Seven Years War (1563-1570) the populace finally warmed to the rulers from Lübeck. Denmark and Lübeck was allies in the war and the castle's commander Sweder Ketting reformed the militia and built earthworks and beacons along the coastline. Several Swedish landing attempts was twarted and the Island remained relatively peaceful during the war.

By 1575 the 50 year period was over and Bornholm and Hammershus returned to the Danish crown. 

War with Sweden and the rebellion

From 1575 Bornholm became a fiefdom under the Danish Crown. The lord of the fiefdom was obligated to pay for the maintainance of the castle. The result was, that Hammershus slowly deteriorated and the defenses was weakened. The artillery pieces was not replaced and by 1610 the garrison was just 13 men.

This was a time of unrest and war between Denmark and Sweden. Bornholm emerged relatively unharmed from the Kalmar War (1611-1613) but during the Torstenson War (1643-1645) the castle was taken along with the rest of Bornholm, but returned to Denmark at the peace agreement. By 1657 Denmark entered the Second Nordic War (1655-1660) and lost to Sweden. Denmark ceded Scania, Halland, Blekinge and Bornholm to Sweden as part of the peace agreement in 1658. In the spring of 1658 the swedes garrisoned Hammershus and Bornholm became a Swedish province. But the people of Bornholm rebelled - encouraged by the Danish king Frederik the 3rd. The rebels conspired to take back Hammershus and the plan was carried out on December 8. The rebels suceeded in capturing the Swedish commander during a visit to Rønne but he was killed by a pistol shot in the confusion. And when the rebels captured the Swedish artillery commander the situation seemed hopeless for the Swedish troops at Hammershus, and after a negotiation they surrendered. Bornholm had freed itself from Swedish occupation.

From castle to ruins

At this time Hammershus was losing its military significance. Cannon was becoming common and the medieval fortress was not built to defend against them. The king built a new state of the art fortress on Christiansø and Hammershus was used as state prison and administrative center for some time. Hammershus was finally abandoned in 1743 and much of the stone and bricks from the castle was broken down and used for other buildings all over the Island. In 1822 Hammershus was declared a national heritage site but by then it was already a ruin.

Modern history

As a result of the industrialisation in the second half of the 1800s many Danish towns was growing. New cobbled roads was built, harbours was expanded with piers of granite and the railroads that was spreading over the country was laid on granite chippings. Much of the granite needed for this came from Bornholm where small and large quarries quickly spread througout the landscape. At Moseløkken granite of a very high quality was produced and on Hammerknuden the huge quarry Hammerværket employed hundreds. By 1892 the harbour Hammerhavn was built to ship the granite.

After the First World War the Danish state bought Hammerknuden after a local group wished to stop the quarrying to preserve landscape and nature. This was not to be - the state rented the area out for further quarrying. But by 1968 Hammerknuden was declared a protected area and in 1970 the quarrying stopped.

Since then nature have taken back much of Hammerknuden. Small and large quarries have filled up with water or have been hidden by vegetation. The steep cliffs at Opalsøen have become a nesting place for gulls. Only the quarry at Moseløkken is still active as one of a few on Bornholm. The qarry museum at Moseløkken tells the story of the rise and fall of the quarry industry.


9.000 - 3.900 B. C.

The Ice Age have ended. Plants, animals and humans return. This is the Mesolitich period and humans are hunters and gatherers. There were numerous settlements all over Northern Bornholm during this period.

3.900 - 1.700 B. C.

The Neolithic period where Man transitions to agrarian societies.

1.700 - 1.100 B. C.

The early Bronze Age. Burial mounds and settlements around Hammersholm.

1.100 - 500 B. C.

The late Bronze Age. A large number of petroglyphs was carved into the bedrock around Madsebakke and Hammersholm.

1050 - 1300 A.D.

Early Middle Ages. Hammershus is built around 1300 A.D.

1300 - 1525 A. D.

Late Middle Ages. Bornholm is ruled from Hammershus by the Arch Bishop of Lund. The Danish king takes the castle several times but is forced to give it back to the church each ime. At Hammerknuden the herring market flourishes and Salomons Kapel is built.

1525 - 1576 A. D.

The german city Lübeck, part of the Hanseatic League, gets Bornholm as a 50 year security for their support. They rule the Island from Hammershus.

1576 - early 1700s A. D.

Bornholm becomes a Danish fiefdom controlled from Hammershus. The Island is involved in the wars against Sweden.

1658 A. D.

Scania, Halland, Blekinge and Bornholm is given to the Swedish as part of a peace settlement. The same year the people of Bornholm rebel. They kill the Swedish commander and liberate the island.

The 1680s A. D.

The royal administration is moved from Hammershus to Rønne and a new stronghold is built on Christiansø. Hammershus continues to be a state prison and judiciary for Northern and Northwestern Bornholm.

1743 A. D.

Hammershus is abandoned.

1822 A. D.

Hammershus becomes a national heritage site.

The 1870s A. D.

Quarrying starts at Moseløkken and on Hammerknuden.


The harbour Hammerhavn is built.

1968 A. D.

Hammerknuden becomes a protected area.

1970 A. D.

The quarrying at Hammerknuden stops.

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