In Ireland and Scotland crannogs were common from the first millenium BC and some continued in use until the 17th century AD. These are artificial islands built in lakes and estuaries that usually held a single roundhouse which could offer sanctuary and safe storage for the family and its livestock. More than 500 have been recorded in Scotland and similar numbers in Ireland.
In some cases an artificial island was made-up using earth and stones, while others were composed of alder piles driven into the lake bed, and braced to form a platform above the water-line. Llangorse Lake crannog in Breconshire, the only known Welsh example, has yielded dates from the 9th century AD for a timber platform and a palisaded enclosure: it seems to have been a residence of the Irish-descended royal house of Brycheiniog.
In some cases an artificial island was made-up using earth and stones, while others were composed of alder piles driven into the lake bed, and braced to form a platform above the water-line. Llangorse Lake crannog in Breconshire, the only known Welsh example, has yielded dates from the 9th century AD for a timber platform and a palisaded enclosure: it seems to have been a residence of the Irish-descended royal house of Brycheiniog.