Clonmacnoise: Medieval Monastery Still Standing After 80 Attacks by the English, Irish, Vikings and Normans!
Clonmacnoise is a medieval monastic site located in County Offaly in the Irish province of Leinster. This monastic site is recorded to have been founded during the middle of the 6th century AD, though the area itself is reckoned to have already been inhabited at a much earlier point of time.
Source: ancient-origins.net