The oldest Roman lighthouse still in use.

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

One of the few remaining ancient aqueducts described by Frontinus as 'the most solemn testimony of the Empire.'

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.

A wooden hut from the Heroic Age of Antarctic Exploration.

One of the most extreme deserts in the world, these snow-free valleys harbor life, despite the hostile environment.

Antarctica's bustling metropolis, originally established by Richard E. Byrd.

Nimrod Polar Expedition base, and home to hundred-year-old frozen whisky.

Naked scientists race around the pole in the frigid cold to try to join Antarctica's exclusive 300 Club.

Natural time capsule containing an alien ecosystem.

An Inca spa, military outpost or maybe… both?

These steeply terraced ruins are a stop along the Inca Trail to Machu Picchu.

The stones of this Incan wall complex fit together so well you couldn't fit a piece of paper between some of them.

Preserved Inca city and site of the last Inca stronghold against the Spanish conquistadors.

The intricate stonework of Machu Picchu serves as a testament to Incan engineers.

105-foot wide giant metallic flower blooms anew every day in the heart of Buenos Aires.

A bright little alley in La Boca is a part of tango history.

Buenos Aires' city of the dead contains some very famous remains, including Eva Perón.

World's largest working waterwheel has been around for over 150 years.

The only medieval bridge in Britain with its defensive tower still in tact.

A tiny village in Wales claims the name of a noble medieval hound slain for a crime he didn't commit.

The longest and tallest aqueduct in Britain can actually be sailed across.

This Welsh village gave itself a ridiculous name in a publicity stunt a century ahead of its time.