The islands all fall within the Shetland Islands Council local authority. They have been continuously inhabited since Neolithic times and experienced Norse rule for several centuries, the first written records being the Norse sagas. The excavations at Jarlshof near the southern end of the Mainland have provided archaeological evidence of life in Shetland since Bronze Age times and the annual Up Helly Aa fire festivals are a living reminder of Shetland's Viking past. The archipelago is exposed to wind and tide and there are numerous lighthouses as an aid to navigation. A small wind farm in Shetland recently achieved a world record of 58% capacity over the course of a year. The indigenous Shetland ponies are reputed for their strength and hardiness.