In Assassin's Creed Valhalla you can come across Cairns that will give you extra points. On this page of our guide, you will find out where to find cairns locations in the Vinland region.
You will find the cairn in the western part of the region, right next to the synchronization point.
It is a very simple task. Arrange the stones so that the entire structure breaks through the blue marking. On the screenshot above we showed the most optimal construction, nothing should happen to it. In this case, the stones vary in size, so it is easiest to arrange them from the largest to the smallest.
This will give you an extra skill point.