A long stone-built gallery with a slab roof, below ground level. It was usually, perhaps in its earliest stages always, associated with a settlement of the Broch culture. Such galleries are widespread in Ireland, Scotland, and the highland zone of Britain, and seem, to show an immigration up the Atlantic seaways from western Gaul in the last centuries BC. In Cornwall they are called 'fogous' and considered locally to be refuges of the 2nd-1st centuries BC; in eastern Scotland they are misleadingly known as Pictish houses. In Brittany, the earliest are of the mid-1st millennium BC. Mainly they were used for cold storage.