All that remains of this once-booming mining town are the ruins of a saloon.

One of the best-preserved Roman amphitheaters is still used today, but for less brutal events.

The remnants of the base where US Army troops learned how to fight in extreme conditions.

These decaying bridges 1,000 feet high are a reminder of the skill it took to cross the Colorado Rockies by rail.

This old train trestle and collapsed tunnel once allowed the railroad to negotiate the steep slopes of the Colorado Rockies.

For decades, Puerta del Sol has been illuminated by a giant, guitar-wielding bottle of sherry.

Few things look more out of place than the electric blue ponds in the reddish-brown desert of Utah.

Visitors flock to the historic birthplace of radiobalneology for its therapeutic radium treatments.

A monument to the three wars that led to German unification towers within a Berlin traffic circle.

This communist behemoth is the heaviest building in the world and a legacy of a brutal regime.

These magnificent city walls rise from the barren sun-baked Spanish plains like something straight out of a fairytale.

St. Mary's features one of the most spectacularly decorated cathedral interiors in all of Europe.

A magnificent, long-abandoned castle built in the wake of the reconquest of Spain.

This hauntingly beautiful cemetery outside a medieval citadel is full of winding paths and ivy-covered graves.

Nine centuries-old fortresses guard the walls of this medieval Romanian city.

The big toe of this towering monument to a Croatian national hero is worn from years of superstitious rubbing.

Paleoamericans built these ancient walls high in the Colorado Rockies as part of an extensive hunting system.

A fire once nearly devoured this gorgeous 14th-century Gothic cathedral.

The largest Art Nouveau complex in the world is a Barcelona hospital with a 600-year-long history.

Every hour the doors open to reenact the legend of the heroic mayor who saved his town by drinking a gallon of wine.

The possible imprisonment of Vlad the Impaler here earned the medieval castle its nickname, "Dracula's Castle."

Horrifically creative torture devices and shame punishments line the walls of this chilling museum.

The iconic boulevard is the perfect place to catch sight of a bicycling skeleton, a levitating Satan, or a chef with his head stuck in a pizza.

This elaborately decorated, fairytale-like Romanian royal palace is one of the most striking castles in Europe.