A roaring, awe-inspiring double cascade of icy water flows through woodland Oregon like something out of a Tolkien novel.

A man-made island in scenic San Francisco Bay.

Allowing humans and fish alike to migrate from freshwater to saltwater and back again.

This blowhole is supposedly caused by a trapped monster.

Erotic art covers the walls of the largest ancient pleasure palace.

Gladiators battle and chariots race daily in the ruins of a once-great Roman city.

Cave carved out of a huge snow drift collapsed killing one and injuring five in July 2015.

Jesus' footprints and the first catacombs in the world.

Japanese national treasure originally built in 593 CE.

Secret North Korean passage discovered below the world's most dangerous border.

A chilling monument to Korean patriots who resisted the Japanese occupation.

Home to more than 13,000 pieces of war memorabilia and military equipment.

One man's exploration of the human form, including the bizarre and delightful "Man Attacked by Babies."

Home to three historic ships from the age of Vikings.

Whitewashed mosque contains the world's largest carpet.

Construction of Barcelona's iconic (but controversial) church is expected to be completed in 2026—a century after the death of its architect.

Peace Park and the Atomic Bomb Dome.

2300-year-old Roman road connecting the empire.

Monasteries on rock pillars, once accessible only by frayed ropes.

Northern Ireland's Brobdingnagian stepping stones.

Dublin's "Dead Zoo" serves as a window to Victorian museum design.

Some of the saint's blood and bones are said to reside in Dublin.

One of Ireland's most infamous prisons for rebels including men, women and children.

The ancient tomb acts as a calendar that keeps perfect time.