These fortifications once served as prehistoric sanctuaries. When danger threatened, people withdrew to them and entrenched themselves here. Most were built around 500 BCE.
The remains of Gråmur hillfort consist today of a semi-circular wall of stone. The drystone walls were built by stacking stones on top of each other without mortar. You can see the remains of the wall among the tumbled stones. You can also see that the hillfort builders took advantage of the natural slopes, which provided good protection from intruders.