The second-longest continuous wall on the planet protects a hidden secret in the deserts of India.

A complex of six forts embedded in the Rajasthan hills.

This strategic isle was once swapped between empires and almost entirely destroyed in a bomb explosion.

This natural "sea of stones" was once used by the Romans as a quarry.

Marvel at the opulent Art Nouveau interior while dining on dirt-cheap French classics.

For more than a century, revolutionary graffiti has marked the wall of a Parisian church.

The remains of the medieval wall that once surrounded Paris with ties to the construction of the Louvre.

The industrial architecture honors the laborers who brought the Exposition Universelle of 1900 to life.

A mammoth WWII anti-air defense tower has been repurposed as a hotel with a rooftop garden.

A series of playful yellow penguins share a serious message about the environment.

Straight out of a nightmare, barcode-faced babies climb up and down Prague's television tower.

Looming communist pillar with a Czech twist.

Monument to a suicide protesting the Soviet invasion.

A historic and beautiful Art Nouveau chamber in a historic railway station.

This Prague museum collects brutalist relics and memories from the country's former Soviet rule.

A turn of the century building boasting some of the most beautiful art nouveau architecture in Prague.

A significant example of Czech cubist architecture—a style you won't find anywhere else in the world.

Tiny memorials honor individual victims of the Holocaust.

One of downtown Berlin's last reminders of its Communist past.

This classic restaurant features a gorgeous mirror-clad room.

The tombstone of an unfortunate explorer who disappeared in the Paris Catacombs.

For more than a century, Parisians have come for affordable dishes in a grand converted train station.

Synagogue built from the stones of Solomon's temple contains the golem of Prague.

Around 100,000 bodies are buried below the medieval headstones, many of which mark graves with multiple bodies stacked up to 12 deep.