The biggest and deepest Cold War bunker open to the public can be found in southeast England.

High atop the Eiffel Tower is a small apartment built exclusively to entertain the science elite and make the rest of Paris jealous.

This charming cobbled backstreet is the most Instagramable street in Paris, much to the residents' annoyance.

The oldest stone house in Paris was built by its most famous alchemist.

This iconic Parisian bookstore doubles as the "Tumbleweed Hotel" for traveling writers.

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

Madrid's romantically ornate crystal palace has been offering shelter to plants and art for over a century.

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

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

This semi-secret storybook hedge maze is also the oldest garden in the city.

A massive display of meteorites all found in the Atacama Desert.

The Chilean mountain is freckled with (relatively) small European telescopes.

Pablo Neruda's custom-built lover's nest was made to remind him of the sea and named after his mistress' hair.

One of the world's most advanced radio observatories sprawls across the Atacama Desert.

An unrecognized micronation declared by Greenpeace to protect the glaciers of Chile.

Named for the DeFoe novel inspired by a stranded sailor, this island is known for its rare plants and extreme beauty.

Antarctica's only sculpture garden, it has art and penguins, but no plants in sight.

Scientists use one of the saltiest bodies of water on Earth as a terrestrial base for studying water on Mars.

The best place to send your postcards home from Antarctica.

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

One of the world's southernmost bars.

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

This 14th-century temple is also known as the "Temple of the Golden Pavilion" for its gorgeous gilded reliquary hall.

Constructed thousands of years ago, these stone circles offer incredible insight into the lives of the people who built them.