O'Brien 's Tower is a round stone tower near the midpoint of the cliffs built by Sir Cornelius O'Brien , a descendant of Ireland 's High King Brian Boru , to impress female visitors .
O'Brien 's Tower is a round stone tower at the approximate midpoint of the cliffs . 
 It was built by Sir Cornelius O'Brien , a descendant of Ireland 's High King Brian Boru , in order to impress female visitors .