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Llangors Crannóg (Wales)

The Medieval Man-Made Island of Llangors Crannóg


Llangorse Lake, Brecon Beacons National Park, Powys, Wales

Llangorse Lake, Brecon Beacons National Park, Powys, Wales

Alan Weybourne
The archaeological site of Llangors Crannóg (also spelled Llangorse Crannóg) is located near Llangors Lake, within the Brecon Beacons National Park in Powys, Wales. On the north edge of the lake is a small island known as Ynys Bwlc (or 'stockaded island'), measuring 40x30 meters. It is on this island that excavations discovered the medieval island construction of Llangors Crannóg.

Medieval History of Llangors Crannóg

In AD 916, or so it is written in the Anglo-Saxon Chronicle, Aethelflaed, Saxon queen of Mercia, daughter of King Alfred of Wessex (849-899), and widow of Ethelred, sent her army into Wales, to destroy the royal residence known as Brycheiniog and capture its inhabitants. Brycheiniog was located on a stony artificial island (known as a crannóg) floating in the middle of Lake Llangors, called Brecenanmere by the English and Llyn Syfadden in Welsh.

At the time, Aethelflaed was busily amassing property in Northumberland and Wales while her brother Edward was conquering the Danish rulers of England. Eventually, Edward would hold nearly all of what is now Great Britain.

Historical Brycheinog

According to historical sources, Brycheinog was a royal residence for Welsh kings claiming descent from Brychan, son of an Irish father and a Welsh mother. The island was built ca. 889-893 by piling stones and earth on top of brushwood, reeds, lenses of sand, and peat. A palisade of oak planks was set around the edge and a stone causeway led to the north shore of Lake Llangors.

Archaeology and Llangors Crannóg

Modern excavations at Llangors Crannóg were undertaken by a joint team from the University of Wales and the National Museum of Wales. The excavations detailed construction methods and identified additional artifacts such as personal decorative items such as brooches, bone combs and rings of shale and glass, fragments of fabric and plenty of charcoal, attesting to the eventual destruction of the buildings.

The site has suffered from erosion and tourist traffic; recent excavations by the National Museum of Wales at the site promise to bring further information about this interesting site, one of the few Dark Age sites in Wales that can be directly connected to a historical event, the site's sacking by Aethelflaed.


Alan Lane and Mark Redknap. 2001. Llangors Crannóg. Pp. 205-207 in Pam Crabtree (ed.), Medieval Archaeology: An Encyclopedia. Garland Publishing, New York.

Redknap, Mark and Alan Lane. 1994. The Early Medieval crannóg at Llangors, Powys: an interim statement on the 1989-1993 seasons. The International Journal of Nautical Archaeology 23(3):189-205.

This glossary entry is part of the Dictionary of Archaeology.

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