2 Best Sights in County Clare, Galway, and the Aran Islands, Ireland

A vast 2-million-year-old cave, Aillwee is the biggest and most impressive chamber in the region accessible to those who aren't spelunkers. Illuminated for about 3,300 feet, the cave contains an underground river and waterfall. Aboveground, there are a big crafts shop, cheese-making demonstrations, a café, and the Burren Birds of Prey Centre, which puts on flying displays from eagles, falcons, hawks, and owls daily at noon and 3 pm (weather permitting). Discounts available if you book online.

Formed from a drop of water thousands of years ago, Doolin Cave's Great Stalactite hangs from the ceiling like a giant rocky sword. The 24-foot feature is one of the world's longest known free-hanging stalactites, and the cave's star attraction. Tours of the cave run on the hour, and outside there's a walking trail around a working farm.