Cliffs of Moher
One of Ireland's blockbuster natural sights, the Cliffs of Moher run 5 miles along, and soar to a height of up to 650 feet plunging to a sheer drop into the ocean far below. The cliffs are amazingly beautiful and on a clear day you can see the Aran Islands and hills of Connemara. Stop at the high-tech visitor center for orientation (which also offers exhibits on fauna, flora, and geology of the cliffs), and then head out on a hike along the top of the cliffs.