Fyrkat Fyrkat might be the oldest of Denmark ' s former Viking ring castle s . It is located near the town of Hobro some distance from the end of the Mariager Fjord in North Jutland . It is built on a narrow piece of land with a river on one side and swampy area on the others . It could have controlled the traffic on the main land route between Alborg and Aarhus . Layout and construction . Like the other castles ( or forts ) at Aggersborg or Trelleborg near Slagelse it is designed as exact circle with four gates opposite to each other and connected by two wooden roads that cross in a right angle in the exact middle of the fort . A circle road gave access to the wall . In each of the four quarters stood four Longhouse s of the same design arranged in a square with a smaller house in the middle . The inner diameter of the ramparts was 120 meters and the width at the base 12 – 13 meters . They were constructed of three rows of vertical wooden poles . Each pole connected to the next ring by beams . The innermost row was the lowest and the gaps filled horizontal with planks forming a wall to the inside of the fort . The middle row was as high as the earthwork and carried the inner side of the walkway . The earth fill sloped to the inside so the ramparts could be easily accessed from every point of the circle road . The outer row of poles was strengthened on the inside and outside with slanted beams at the base . They probably were higher than the middle row and supported a parapet . The gaps between the posts were again filled horizontally with planks but on the outside there was also a wall of vertical trunks slightly leaning to the wall . The space in between the post rows was stacked with some 10000 cubic meters of turf . On the wall there was a walkway made of planks . The outer wall is presumed to have stood some four meters high . The northeast quarter was protected by a ditch with pointed bottom about 7 to 8 meters wide and under 2 meters deep . The ditch on the west and southwest side was never finished . The other sides were protected by a river and rather swampy area . A structure in front of the west gate my have been a gatehouse of some sort . The roads inside the fort were founded on three to five rows of short poles rammed into the ground and supporting strong beams running lengthwise along the rows . These were then topped by strong planks spanning the width of the road . The circle road along the inside of the ramparts rested on two rows of beams . The 16 identical longhouses were arranged in a square with the corners almost touching . They were 28 . 5 meters long ( 96 roman feet of 29 . 6 cm ) , 5 meters wide at the ends and 7 . 5 meters in the middle , the long walls slightly curved to the outside . The walls consisted of double rows of posts with planks wedged horizontal between them to make a wall . Along the outside ran a row of posts slanted to the wall either to support it at the top like buttress es or maybe even in some sort of cruck like construction being the rafters of the roof . On how the roof was built exactly the opinions differ . It might have been coated with reeds or maybe wood shingles or even a construction of planks similar to the ships . Inside the houses , each end was walled off to make a small room , maybe a pantry or storeroom . The two small rooms had doors to the outside on the short end and could be accessed from the large middle room in the inside . Near the ends of the 18 meters long great middle room each long wall had a door set diagonal to the door on the other side that led into a small porch with a door to the outside . On the inside the great room had a large hearth in the middle and a raised wide bank alongside the outer walls for sleeping . Of the longhouses in Fyrkat at least two contained smithies and gold was worked with in two others . About a quarter of the excavated houses seem to have been warehouses of some sort . Excavation and finds . The site was excavated between 1950 and 1958 by the Architect and Museum Inspector C . G . Schultz . The ramparts , that had almost been ploughed level through the ages were piled up again and the postholes of the roads and buildings were filled with concrete . The museum at Hobro houses most of the things found at Fyrkat . Most was found in the graveyard to the northwest of the fort that had a wooden planked road lead to it . The most precious find was a piece of gold jewelry with nice birds head . In the about 30 graves of men , women and children some were buried in wagon crates such as found in Oseberg others in coffins . The poor were randomly mixed with the rich . Dating . The very similar castle Trelleborg near Slagelse has been dated precisely to the spring of 981 by tree ring dating , Fyrkat might be a year or two older , Aggersborg could be slightly younger . Not enough was found at Nonnebakken to make an exact enough dating possible . Yet the forts are so extremely similar that it seems most probable that they were conceived by a single mind . Fyrkat seems to have been inhabited only for a rather short period of time , maybe not much more than a decade , maybe even less . By the year 1000 the fort seems to have been deserted and shortly after had simply burned to the ground without any evidence of fighting . Today . Besides the ramparts that rather represent just the volume of the original than the construction , a longhouse was reconstructed in 1985 just outside of the fort . It claims to be somewhat more accurate than the first one reconstructed in 1948 at Trelleborg near Slagelse . In recent years a " Viking Center " has been built about one kilometre from the fort . It resembles a large farm with a big longhouse finished in 1993 , a smithy , a barn and some smaller buildings along with a visitors center . Its main aim seems to be educational and thus presenting a complete Viking age environment here on the model of a supplier for the fort . None such farm was ever found near Fyrkat though , the buildings being reconstructed after examples excavated in Vorbasse , a small town in southern Jutland .