Béal Ború, also known as Brian Boru's Fort, is a large earthen ring fort just north of Killaloe on the west bank of the Shannon, commanding the southern entrance to Lough Derg. Excavations have found stone tools from the Stone Age and evidence that a ring fort here was lived in, abandoned and later built over by a bigger bank and ditch in the 11th century. It is thought to be where Brian Boru was born or grew up; as an adult he ruled from Kincora in the town.
The name means "mouth of the cattle tribute". The river could be forded here until its level was raised in the 1920s, and tribute in cattle was probably paid at the crossing, which may also be the origin of Brian's own name. It's a National Monument, about 70 metres across, and an easy walk from town.