An underground, or partially buried, curved like a banana chamber mostly made of stone. These are of unknown function, ; suggestions have been made that include ritual, (as some contain prehistoric and Roman carved stones), refuges from danger and as granaries. They are commonly found in Scotland - though a possible example was found at Milfieldhill, (Northumberland), in 1828AD as part of the Agricultural Revolution in that area. However, this was not recognised as such by early antiquarians. They were dug into sloping ground; sometimes earlier hillfort defences. They, in Scotland, date from the late Iron Age to possibly the early Medieval period. There are possible parallels in the southwest of England - though here they are called fogous.