‘Fogou’ is a Cornish word meaning a cave, and Cornish fogous are
prehistoric underground passages constructed by excavating a trench
and lining its sides with either large stone blocks or drystone
walling, and then roofing this passage with large flat slabs.
Fogous are often found in association with later Iron Age or Romano-British
period settlements, but modern investigations have done little to
solve the enigma of their function – they may be ritual structures,
or have been used for storage or as a place of refuge.