The Cliffs of Moher are in the southwestern edge of the Burren region in County Clare. They rise 120 metres above the Atlantic Ocean at Hag's Head and eight kilometres to the north, and they reach their maximum height of 214 metres just north of O'Brien's Tower, which is a round stone tower near the midpoint of the cliffs that was built in 1835 by Sir Cornelius O'Brien. From the cliffs, and from the tower, visitors can see the Aran Islands in Galway Bay, the Maumturks and Twelve Pins mountain ranges to the north in County Galway, and Loop Head to the south. The cliffs set amongst the most visited tourist sites in Ireland and receive approximately one million visitors a year.