This one-time health resort was used by aristocrats around the world.

A miniature train-ride through Slovenia's largest cave system.

This massive subterranean fissure is known as the "underground Grand Canyon."

The former private quarters and office of Dr. Sigmund Freud now hosts a museum housing the works of the founding father of psychoanalysis.

19th century pendulum and a clock restored by a rogue group of guerilla artists.

An "inside out" building in the historical center of Paris, featuring Europe’s largest modern art museum.

This enormous censer uses a pulley system installed over 400 years ago.

A 19th-century fortress and collection of artifacts offer a tour of Saudi history.

These towering cliffs jut dramatically from the middle of a barren desert.

Hiding in plain sight near Kathmandu’s government center is a giant mandala that has become a locus for political protest.

The oldest Hindu temple complex in Nepal serves as the seat of Nepal’s national deity, Lord Pashupatinath.

This Kathmandu museum, built in an Austrian modernist style, looks like a set from Star Wars.

This historic square in Nepal is home to temples dating back to the third century.

This fortress dates back to the 6th century and is also the site of a controversial abandoned restoration project.

Taking the subway here means doing so over a bridge located in the middle of an estuary.

A gorgeous, Gaudí-esque stairway constructed in the city of Istanbul by a prominent Jewish family.

Climb a steep hill in 90 seconds on the second-oldest urban subway in the world.

Legend says if you stick your thumb in the hole and it gets wet your wish will be granted.

This remarkably well-preserved Egyptian plinth is pretty well traveled for a giant piece of stone.

A marvel of Byzantine engineering under the streets of Istanbul.

The former stronghold of the Malla Dynasty has remained virtually unchanged since the 17th century.

Named after the Goddess of Harvests, Annapurna is the deadliest member of the Eight-thousanders club.

One of the largest Buddhist stupas in the world keeps an eye out in every direction.

Sacred Buddhist home of some spiritual monkeys.