Wikipedia
Hut circle
A hut circle is the archaeological term given to a circular or oval depression in the ground with evidence of a low stone wall around it that used to be the foundation of a round house. The superstructure of such a house would have been made of timber and thatch. They are numerous in parts of upland Britain and most date to around the 2nd century BC.
Hut circles are usually around 5 to 25 feet in internal diameter, with the rocks themselves being 2-3 wide and around 3 feet high. Hut circles were also almost certainly covered by conical rounded roofs and supported by posts that were internal and sometimes external.