What is "randoon"

Randoon is a Turgesius Viking fortress located southwest of Lough Lene in Ireland. The fortress is situated upon a hill in Ranaghan, dominating by its height all other ringforts in the area, and overlooking Lough Lene between the towns of Castlepollard and Collinstown. The locally used term fort refers to any of the multitude of ringforts, many of which have been overgrown by vegetation. These remain today as historical relics Early Medieval Period of Ireland and Western Europe; they protected by Irish national heritage law.