Fyrkat sits on a narrow tongue of land near Hobro, a stream on one side and marsh on the others, commanding the overland trade route between Aalborg and Aarhus. It is a perfect circle. Four gates face each other exactly, joined by two timber roads crossing at right angles in the precise centre, with a ring road running inside the rampart. The inner diameter is 120 metres. Trelleborg near Slagelse, built to the same plan, has been dated by tree rings to the spring of 981; Fyrkat may be a year or two older, Aggersborg slightly younger. The forts are so nearly identical that they can only have been conceived by a single mind — almost certainly Harald Bluetooth's, possibly his son Sweyn Forkbeard's. In 2023, UNESCO inscribed Fyrkat on the World Heritage List alongside Aggersborg, Trelleborg, Nonnebakken, and Borgring, five expressions of one royal idea.

Sixteen longhouses stood inside the ring, four to a quarter, arranged in squares with their corners almost touching and a smaller building in each courtyard. Every one measured 28.5 metres long — ninety-six Roman feet of 29.6 centimetres, which tells you something about who was doing the measuring. Their long walls bowed gently outward, five metres across at the ends and seven and a half at the waist. Inside, a hearth burned in the middle of an eighteen-metre hall lined with raised sleeping banks; small storerooms were partitioned off at each end. The rampart itself was an engineering exercise: three rows of vertical posts tied by beams, the gaps planked, some 10,000 cubic metres of turf stacked between them, and a plank walkway on top of a wall thought to have stood about four metres high. On the northeast side a ditch seven to eight metres wide was cut. On the west and southwest it was never finished.

Northwest of the fort, a planked road ran out to the cemetery, its post holes still traceable in two parallel lines. Around thirty burials survive there, all laid east-west, though shallower graves were common and more have surely been lost. Eighteen show traces of a coffin. Some of the dead were laid in wagon bodies, the same practice found at Oseberg in Norway — a cart to carry you onward, and a mark of standing. Only one weapon turned up in the whole cemetery. Most of what people took with them was domestic: beads, brooches, keys, boxes, knives, whetstones. Graves shorter than 150 centimetres are read as children's. The striking thing, given a fortress built by a king, is the arrangement: the poor lie mixed in among the rich, without any visible segregation.

Her burial is the one archaeologists keep returning to. The wand, the henbane, the amulets shaped like chairs, the white lead in her belt buckle that may have been a skin ointment, the imported bowls and the Gotlandic brooch full of owl pellets — read together, the assemblage points toward someone who practised sorcery, the figure Old Norse sources call a völva. That reading is an interpretation, not a signed confession, and it rests on objects rather than words. What is beyond argument is her reach. Bronze from Central Asia and a brooch from Gotland ended up in a grave in Himmerland, which means the community at Fyrkat was wealthy, connected, and in contact with a world far larger than the marsh at its gates. Whoever she was, the people who buried her thought she needed her tools.

Fyrkat did not last. Occupation seems to have run for barely a decade, perhaps less. By about the year 1000 the place stood empty, and shortly afterward it burned to the ground — with no evidence at all of fighting. Whether that was accident, deliberate clearance, or ritual closure, nobody can say. The ramparts were ploughed nearly flat over the following centuries until C. G. Schultz, architect and museum inspector, excavated the site between 1950 and 1958, rebuilt the earthworks, and filled the postholes of the roads and buildings with concrete so the plan could be read from the ground. In 1985 a longhouse was reconstructed just outside the rampart, and in 1993 the Viking Center opened about a kilometre away: nine buildings modelled on excavated farm structures from Vorbasse in southern Jutland, since no Viking farm has ever been found beside Fyrkat itself. Most of the finds, including the woman's, are held at the museum in Hobro.