Vortex-shaped aquarium hosts Europe's largest school of piranhas and other ocean creatures.

A walkable map of the world, made from soil and stone by one man.

A 19th-century subterranean reservoir repurposed as a contemporary art cave.

It's said this geological anomaly was caused when the Devil took a bite out of the Irish mountainside.

After it was swallowed by a Georgian mansion, this medieval castle remained forgotten for centuries.

These moss-covered medieval ruins tower atop the smallest of Ireland's Aran Islands.

A Neolithic passage tomb said to have sheltered two legendary Irish lovers.

A massive Celtic cross secretly growing in an Irish forest.

This natural sea arch highlights Ireland's rugged coastal beauty.

A strange egg in a mucky bog of western Ireland marks the spot of an aviation milestone.

This 14th century tower house was once the home of Irish poet W.B. Yeats.

Impressive mining ruins overlook a spectacular view of Ireland's Copper Coast.

An ancient holy well said to be used by the patron saint of sailors and travelers, lost in the boggy west of Valentia Island.

The modern birthplace of Irish freedom.

A devastating booze inferno poured through the streets, claiming several victims who drank it.

These imposing walls and towers look more like the ruins of a fortress than a monastery.

The skeleton of a whale that beached itself in this Irish town is now on display in their public park.

Mortarless walls that stretch for miles are a lovely solution for creating grazing land in the harsh terrain of the Aran Islands.

Oliver Cromwell once seized the land under this house, which included the ruins of a medieval abbey that the owner used to build his stately home.

Ruins battered by centuries of war and disaster offer a wondrous glimpse of medieval Ireland.

Ireland's most remarkable collection of these curious cone-shaped houses is worth the buzz.

Though they've since been renamed, these two streets hint at Dublin's darker days.

A spectacular hidden beach in Ireland has the dark, disturbing nickname of "Murder Hole Beach."

You can see three Irish counties from this Neolithic hillside fort, once the seat of the Kingdom of Ailech.