The summer tourists on these cliffs are thousands of seabirds.

Cairns built to bring travelers good luck stretch across the land like miniature stone mountains.

Thousands of exquisitely carved stone water storage wells, hundreds of stone steps fill this exquisite medieval stepwell.

Keshwa chaca, among the last handwoven Incan bridges, crosses Apurimac Canyon in Peru.

Strange rock formations tower above the river that snakes through this enchanting Icelandic canyon.

This maze-like slot canyon is a unique gem within an already fascinating geological area.

A strange rock with a sinister reputation lurks within the crimson waters of this Scottish glen.

A 600-year-old mini shrine guarded by a sword-wielding knight hides in a crumbling cliff face.

An isolated 17th-century chapel on a remarkable site once dedicated to Celtic sun worship.

Take respite inside this jaw-dropping church while climbing the volcano where Georgia's Prometheus was once chained.

Legend says these stone structures are where the doomed citizens of a vanished village sent themselves to die.

The ruins of the castle that chemicals built.

A popular winter vacation destination for migrating monarch butterflies.

The first attack on the continental U.S. during WWII occurred off the coast of a quiet California golf course.

Windswept and remote, this island was once the home of a rare mammoth and today is home to a rare tree.

The last inhabitants of one of the U.K.'s most remote islands were evacuated in 1930.

Now abandoned, the first public health hospital in the U.S. saw more than one million immigrants from around the world.

This abandoned Greek island was the last active leper colony in Europe.

A hollowed-out baobab that became the horrific final resting place of leprosy sufferers, with gruesome evidence to prove it.

A secluded natural oasis hidden deep along a rainforest trail.

A science fiction-inspired apartment building designed by a famous Spanish architect.

This Seattle joint serves food inside an old train car once used by FDR.

The mummified heart of Louis XVII, the lost dauphin of the French Revolution.

The curious underground history of keeping Paris clean.