This ancient theater, restored in the 20th century, lives on as a venue for dramatic and musical performances.

An abandoned saucer-shaped monument in the Bulgarian mountains.

The deepest underground city in Turkey was designed to protect 20,000 people behind massive stone doors.

In this historic region, homes and churches are carved into ancient volcanic rock formations.

Roman ruins top white travertine terraces formed by ancient hot springs.

A musical instrument played by the sea.

A well-preserved medieval village nested on a rocky outcrop and surrounded by a network of cliffs, natural bridges and canyons.

Historic medieval fortified city in southwest France.

Giant eggs, walls of bread, and nightmare surreality mark the largest collection of works by Salvador Dalí.

Haunting monument to the German Jewish philosopher who died while fleeing fascism.

Wonderland replication in progress by one persistent man.

Mountain where Jesus was first tempted by the Devil.

Gaudí's famously flamboyant architectural style is on full display in this sprawling park and garden.

These secluded and abandoned anti-aircraft defenses have become one the most scenic viewpoints in Barcelona.

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

A 'living museum' in Leiden, the oldest of its kind in the Netherlands.

The works of poetry's biggest names grace the walls of the city of Leiden, all carefully painted by hand.

Oldest Museum of the Netherlands is a true cabinet of curiosities.

This historic Amsterdam bar used to accept sailor's monkeys as payment.