Gordon Sleight, projects leader for archaeology and history group Historic Assynt, in the north west Highlands, said: "Under a strange layer of clay, we came down to a 1.5 metre square, one metre deep pit dug into the ground with a channel to feed water in from a nearby burn [stream], plus three slabs which may indicate it was once lined with stone.
     The find was made by the Fire and Water Project, which is run by Historic Assynt, while trying to understand what a crescent shaped mound of stones had been created for.
     "There were no animal bones or anything to suggest its use as a cooking site and its size would have made it well-nigh impossible to bring to boiling point. So warm water is more likely, which suggests it was used for bathing, or perhaps as a sauna or sweat lodge."
     Other possible uses include cooking and feasting, or perhaps brewing. Such sites are common in Ireland, where they are known as 'fullacht fiadh', or burnt mounds, the crescent being formed of discarded fire-cracked stones used for heating the water.

Edited from BBC News (17 October 2012)