At the heart of symbolism

Trelleborg, the Viking fortress

(Detailed page)


The fortress layout

The fortress was built on a site that conceals pits full of human and animal skeletons. However, the pits had to be filled and levelled before the construction could start. That would not have happened in a religious earth and confirms that the builders were not Christians. They were not anti-Christians either, for the most radical migrated to Iceland or elsewhere.

The archaeological study of the site showed that the promontory on which Trelleborg had to be built was mainly filled with earth on its south-west side. That means that the builders spared no effort to build the construction as close as possible to the plans.

The fortress consists of two parts:

  • An inner work surrounded by a massive circular rampart with a wide and deep ditch:
    • Inside the rampart, four gates face the four compass points. They are connected two by two by perpendicular streets which divide the circle into four equal quarters;
    • In each quarter, we find a block of four identical houses arranged in a square; they are made out of wood and shaped as a reversed ship. These houses served as quarters for ship crews. A similar smaller house lies in the north-east quarter. In the middle of the north-east and south-west blocks stands a little rectangular house, probably reserved to the chiefs. At the north and west gates, two small square houses were likely used by sentries.
  • A less impressive outer work made of a lower rampart with a shallow ditch and shaped as an arc of circle going from south to east:
    • Along the rampart, thirteen similar and smaller houses than the preceding ones seem to radiate from the centre of the inner work. Two similar houses lie in parallel on either side of the east-west axis. They are separated by the same distance as the corresponding houses within the circle. All these houses could have been used by craftsmen and peasants;
    • In the square extension to the east of the work, lots of graves have been discovered. They have no Christian character despite their east-west orientation. Indeed, these graves are facing the sea as well and that is probably why Viking graves are often east-west or north-south oriented.

At the Viking time, the fortress had one entrance only. It was located south where the traces of a bridge over the outer ditch were found. It was prolonged by a second bridge over the inner ditch to reach the south gate. The inhabitants could also get over the inner ditch through a south-east bridge.

What does the plan reveal ?

The Norse tradition dips its roots into Life, Destiny and Wisdom. Let us see how far the fortress structure and the tradition throw light on each other.

The site

Summer and winter solsticesThe fortress was built on a site where lots of traces of a great Stone Age settlement have been found. In fact, the place is full of physical remains wrapped in an indissociable cultural context.

Now, the “solstitial rectangle”, determined by the sunrise and sunset position at the solstices, is practically a square at the latitude of the site (φ = 55.4°) 1. As noticed before, the chief houses stand in the middle of the north-east and south-west blocks and, therefore, on the corresponding diagonal of the solstitial rectangle. In all likelihood, the Vikings from Trelleborg celebrated the solstices and probably privileged the highly symbolic axis linking south-west to north-east. The summer solstice sunrise marked the last day of the sun's ascent towards light before its descent towards darkness; the winter solstice sunset the end of its descent towards darkness before a new ascent towards light. The solstices symbolized the bridge linking the worlds of light and darkness at specific moments.

The inner work

The layout of the inner work looks like a wheel with four spokes (extending beyond the circle). It is nothing but the projection on a horizontal plan of a sphere marked out by the three axes crossing at its centre and representing the cosmic world. It follows that the wheel depicts the terrestrial world and its four compass point directions within the celestial sphere. A sphere used as a framework of the world and human destiny.

The main entrance to the fortress is south and south-north oriented. The south-north axis corresponds to the projection on the horizon of the directions pointing towards the midday sun on one hand and North Star on the other hand; it links diurnal and nocturnal orientations. The axis also connects the worlds of daylight (east-south-west) and darkness (west-north-east), the worlds of the living and the dead separated by the east-west axis, the half-light and half-darkness axis. That could also explain why the dead people in the burial ground to the east lie along the east-west axis.

Indeed, in the Viking society, death was not an end but a passage to a higher being's state giving full access to one's destiny. Vikings happened to know the true meaning of their life only after their death. Then, they saw clearly all the threads that wove the canvas of their fate; they got to know their place in the destiny of the universe and beings. Before they knew what they had to do; after they understood why they had to do it.

Moreover, some living could, on certain occasions, undertake a voyage to the dead kingdom. A journey full of pitfalls and resembling an initiation course. It was the case of Thor, son of Odin, who wanted to get the knowledge, inaccessible to the living, from the giant Geirrod.

Conversely, some dead were temporarily able to leave their world to inform the living. Although Master of destinies, Odin wanted to know the fate of his dead son, Balder, in the other world. So, he forced the clairvoyant Volva to come back on earth for a while and tell him about.

Block of four housesThe solstice celebrations did nothing but maintain the passage between both worlds. As one of the worlds was only the continuation of the other, they had to look alike. A similarity underlined by the strong symmetry of the inner work and based on the use of the square exclusively, the most appropriate symbol of the terrestrial world. Even the curved lengths of the houses relied on the square, for it had probably been realized from ellipses. As two adjacent houses necessarily had a focus (of the ellipse) in common, the four foci required to build a block had to be the vertexes of a square (see the drawing). It follows that the whole plan of the fortress could be drawn on the ground with the help of posts and ropes only.

The outer work

The thirteen houses of the outer work seem to radiate from the centre of the inner work. This architectural radiance prefigures the expansion of the Viking territory in various directions.

The centre of the wheel inside the inner work depicts the motionless point around which the spokes are turning. It represents the terrestrial image of the immutable point, from which everything is coming and to which everything is going back. It symbolizes the beginning and the end, the point where everything is unified and reunified. More prosaically, the centre characterizes the place where the Vikings prepared their expeditions and rested after their return.

Two other houses lie on either side of the east-west axis. Their parallelism underlines the correspondence between the world of the living and the world of the dead. Two worlds separated by a passage that people of the North symbolically crossed by boat.

1 back At the solstitial sunrise and sunset, the angle formed by the south-north axis and a diagonal of the solstitial rectangle can be determined from the following formula (see the position on the celestial sphere):

cos a = - sin (δ)/cos(φ)

Where φ = 55.4° and δ = ±23.5° at the solstices, that is:

a = cos-1 [sin(23.5°)/cos(55.4°)] = 45.4°

It follows that both diagonals make an angle of 2×(90°-45.4°) = 89.2°.

The boat symbol

The Viking ship constituted an essential means of travelling in marine areas. It was the result of an unmatched art and technique at the time. Without it, the Viking people would not have existed. The ship could:

  • Shape, in its reversed form, the roofs of houses;
  • Delineate graves in burial sites;
  • Be used as grave for high ranked persons of the Viking world.

The Danish National Museum has attempted the reconstruction of one of the houses of the outer work, close to the entrance of the fortress. The rooftop represents the curve of the celestial vault and refers to the higher being's states. As in various traditions, the ship sailing on the higher celestial waters is like the reflection into water of the boat floating on the lower terrestrial waters.

Lindholm is a major Viking burial site overlooking the city of Aalborg in Jutland (Jylland). The majority of the discovered burials are cremations and some inhumations. Most of the graves are surrounded by stones. The shape drawn by these stones and its dimensions depended on the status of the dead person. The women's graves are round or oval whereas the men's are shaped like Viking ships or as a triangle (or ship bow).

The boat-grave of a Viking chief can be seen in the Viking Museum at Ladby, located on the north-east coast of Funen (Fyn). He was buried in his ship with his finest objects under a mound of earth around 925 of our era.

In Norse mythology, Balder's dead body was laid in a boat to which fire was set before being launched on the open sea. The boat was used as a mean of passage between the worlds of light and darkness, the world of the living and the world of the dead.

The boat is the symbol par excellence of the passage from a being's state to a higher one. This passage could be carried out either at the time of someone's death or during the initiation process in the course of the lifetime of a few elected. An initiation within a non exclusively warlike tradition.

The fortress of Trelleborg was before all a defensive construction where its occupants liked to meet each other. They spent time recovering and training for battle, but also practised rites linking the world of the living to the world of the dead. The Vikings were deeply committed to the Norse tradition. They did not try to impose their beliefs neither to change them. They were never engaged in a war against Christianity. They even ended up adopting the Christian religion. In fact, it was rather the leaders who converted themselves, mostly for political and/or economical expediency reasons, than the Viking peoples. The material preoccupations held an important place within their societies. The Vikings wanted to get rich by all means (trade, service of mercenaries, looting, payment of tribute or ransom etc.), but the material wealth did not mask another wealth which fed them just as much.

The construction of the Trelleborg fortress

The following video on the construction of the Trelleborg fortress is a documentary by Rune Kreim Larsen in Danish with English subtitles.


  • Poul Nørlund:
  • “Trelleborg”. National Museet, 1968;