Remnants of the most densely packed city in world history, that thrived on anarchy for 30 years.

One of the biggest markets in Asia, under one of the continent's largest domes.

Khmer Rouge's high security prison.

5,000 skulls in memorial to those killed by the Khmer Rouge.

A battle between nature and architecture in the Cambodian jungle.

This medieval manuscript collection has some of the most obscure and ancient texts in the world.

The world's smallest drawbridge.

An early 20th-century bullring converted into a modern shopping center.

This amazing example of Valencian Art Nouveau looks more like a cathedral than a public market.

A contemporary art installation housed within a Gothic cathedral.

Giant topiary dog once played a role in a terrorist bomb plot.

Giant granite sculptures representing family on the northern coast of Spain.

The oldest Roman lighthouse still in use.

Devastated landscape used for hundreds of years by the Romans as their primary mining site.

A vista of the city and sea from atop the little-known viewing deck on an unassuming Columbus statue.

This house's itty bitty size means no humans allowed.

A lush indoor jungle fills this bustling Madrid transportation hub.

The oldest restaurant in the world is this old-world Spanish eatery, still known for its suckling pig.

An ancient Egyptian temple in the middle of Madrid, Spain.

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

One of Antoni Gaudí's most classic buildings is well-known for its "dragon-back" design.

Construction of Barcelona’s iconic (but controversial) church was finally completed in 2026—a century after the death of its architect.

Vienna's giant wonder wheel had a starring role in one of the greatest noir movies of all time.

A tropical paradise just a short trip from the opera house is filled with beautiful winged creatures.