A crannog is the name given in Scotland and Ireland to an island, either artificial or natural, used for a settlement and usually linked to shore with a timber gangway or stone causeway. The name can also be used to refer to wooden platforms erected on shallow loch floors, although understandably few remains of this sort have been found. The choice of an island as a home is thought to have been for defence as well as the availability of food in the form of fish nearby.
The islet of Eilean Domhnuill, Loch Olabhat on North Uist may be the earliest crannog, dated to 3200-2800 BC in the Neolithic period. Most crannogs were in use from the Iron Age through to the early Medieval period, at about the same time as the brochs, the wags, duns and the larger roundhouses.
The highest concentrations of crannogs (in Scotland) are found in several lochs within Dumfries and Galloway region, although many have been found in the highlands as well.
A reconstructed crannog is located in Craggaunowen, Ireland.