massive stone wall was probably built in the Christian era, but the bank and ditch
surrounding the fort date to the early Iron Age
On the top of the Greenan mountain, not far from the border of Northern
Ireland, lies Grianan of Aileach, one of the finest stone forts in Ireland. From the hill-top
there are commanding views over Lough Foyle, Lough Swilly, and Londonderry,
about 8km (5 mi) to the East.
The massive stone wall is 3.9m (13ft) thick and encloses an area 23.4m (77ft)
in diameter. In the walls are small chambers; a series of stairs
at regular intervals inside the walls gave access to the
wall-walk. The entrance is very long and lintelled.
Legend says it was built by the ancient gods; the ring fort was known
as the Sun Palace and was held sacred. Traces of ancient earthworks, dating to the
early Iron Age, surround the fort, enclosing an area of about 5 acres (0.02 km2).
The fort itself was probably built in the early centuries of the
Christian era. From the 5th to the 12th century AD it served as the royal
seat of the O Neill sept of Aileach; it was destroyed by Murtogh O Brien,
king of Munster in 1101. To make the demolition complete, the king ordered
each of his soldiers to take away a stone from the fort. Grianan of Aileach
was reconstructed by Dr Bernard of Derry in 1870, but archaeologists are
doubtful about the inner restoration.
Surrounding the stone fort
are three concentric low walls which formed part of the original fortification
of the fort.