A few minutes north of the gallows hill, on a stretch of grassy coastal cliff, sits a perfect spiral of head-sized stones some 18 metres across. There is no entrance fee, no signage barriers, nothing official about it — just a strange piece of pre-Christian folk geometry sitting on the headland with views across to the lighthouse.
Walking the spiral in and out takes about ten minutes if you stay slow, which is what the original purpose seems to have called for. Combine with Galgberget for a good morning's wander outside the walls.