The ruins of this medieval castle in Northern Ireland have inspired artists from C.S. Lewis to Led Zeppelin.

This short bridge is the only thing connecting a tiny Irish island to the mainland.

Northern Ireland's Brobdingnagian stepping stones.

The atmospheric road was never meant to be so creepy.

The castle still holds traces of the abandoned Roman fort it was built atop.

Recently restored menagerie of Victorian-era beasts.

A harem-inspired Moorish fantasy design in a Victorian-era Welsh castle.

Open since 1938, this diner has kept its fountain, malt machine, and all the gum that greasers left beneath its counter.

The first permanent memorial to a unique secret weapon of World War II.

This innocuous New Mexico storefront was once the secret jump-off spot for Manhattan Project scientists.

These Pre-Columbian petroglyphs contain representations of birds, deer, hunters, and even some early Native flute players.

An immersive environment that is part haunted house, part choose-your-own-adventure, and part jungle gym.

This iconic 1958 tower welcomes air travelers to Tucson with neon-lit letters and architectural style.

Make a wish at what might be America's only Catholic shrine to a sinner.

Legend says train robbers stashed their gold within the depths of this unusual cave.

The highest point in Arizona is an oddly snow-topped peak within the otherwise arid state.

The fading, forgotten remains of a once bright and booming factory.

The world's largest military aircraft cemetery.

The installation’s official name, “You Who Are Getting Obliterated in the Dancing Swarm of Fireflies,” says it all.

This narrow coastline trail through the dense Kauai wilderness is among the most beautiful and dangerous in the world.

This blowhole is supposedly caused by a trapped monster.

A fitting attraction for the corn capital of the world.

This prehistoric sinkhole lured exclusively male mammoths to their death, much to the delight of science.

One of America's first dinosaur parks gives a window into Depression-era paleontology.