Halliggye Fogou

The largest and best-preserved fogou (underground stone passage) in Cornwall, England, constructed in the 5th or 4th centuries BC during the middle Iron Age. The complex features a 20-metre main sloping passage terminating in a reduced-height creep, plus a 28-metre curving side passage running westward. Built within a farming settlement called a 'round,' the site housed several family groups in four or five houses surrounded by an earthwork enclosure. Pottery evidence indicates the settlement was occupied for 700 years through the end of the Roman period, though the fogou's exact purpose -- whether storage, refuge, or ceremonial space -- remains debated.