The Cliffs of Moher (Aillte an Mhothair, "Cliffs of the ruin") are located in the parish of Liscannor at the south-western edge of The Burren area near Doolin, which is located in County Clare, Republic of Ireland.
The cliffs rise 120 m (400 ft) above the Atlantic Ocean at Hag's Head, and reach their maximum height of 214 m (702 ft) just north of O'Brien's Tower, eight kilometers away. The cliffs boast one of Ireland's most spectacular views. On a clear day the Aran Islands are visible in Galway Bay, as are the valleys and hills of Connemara.
O'Brien's Tower is a round stone tower at the approximate midpoint of the cliffs. It was built by Sir Cornellius O'Brien, a descendant of Ireland's High King Brian Boru, in 1835, as an observation tower for the hundreds of tourists that frequented the cliffs even at that date. From atop that watchtower, one can view the Aran Islands and Galway Bay, the Maum Turk Mountains and the Twelve Bens to the north in Connemara, and Loop Head to the south.
Moher tower, located at Hag's Head, is a square stone ruin. It appears to be the remains of a watchtower placed during Napoleon's reign in Europe.
Interesting fact: The Cliffs of Moher were filmed as the "Cliffs of Insanity" in the 1987 movie, The Princess Bride.