Souterrains

Souterrain (from French sous terrain, meaning "under ground") is a name given by archaeologists to a type of underground structure associated mainly with the European Atlantic Iron Age.

These structures appear to have been brought northwards from Gaul during the late Iron Age. Regional names include earth houses, fogous and Pictish houses. The term souterrain has been used as a distinct term from fogou meaning ‘cave’. In Cornwall the regional name of fogou (Cornish for ‘cave’) is applied to souterrain structures. The design of underground structures has been shown to differ among regions; for example, in western Cornwall the design and function of the fogou appears to correlate with a larder use.

The name souterrain comes from the French language (sous-terrain or souterrain), in which it means "underground passageway" or refers to subterranea in general. In languages other than English, it is sometimes used to mean "basement", especially in warehouses, or semi-basement.

Souterrains are underground galleries and, in their early stages, were always associated with a settlement. The galleries were dug out and then lined with stone slabs or wood before being reburied. In cases where they were cut into rock this was not always necessary. They do not appear to have been used for burial or ritual purposes and it has been suggested that they were food stores or hiding places during times of strife, although some of them would have had very obvious entrances.

An example of an excavated souterrain is the site at Rosal, Strathnaver, Sutherland. In this excavation, no artefacts or other finds were made inside the structure and the roof may have been only partially covered with stones, a timber roof being present on part of it. It was suggested that the souterrain could have been used as a byre or barn and it was associated with an abandoned settlement.

...
Wikipedia