This domed temple was built in a hidden cave mouth as a refuge for sinners seeking absolution.

A star-shaped fortress town fort built in the geometric model of the Renaissance utopian city.

More stones than Stonehenge, all scattered within a windswept landscape sure to enchant 'Outlander' fans.

The mysterious megaliths have enchanted and intrigued visitors for thousands of years.

Legacy of the earthquake that nearly wiped Lisbon off the face of the Earth.

The ruins of this medieval castle on a foggy hill tell the story of a once-mighty empire.

This Slovak bridge is known both for its connection to a national uprising and its UFO-shaped eatery.

This spaceship sculpture in the middle of the Slovakian capital looks like it just crash-landed.

A charming flea market shop dedicated to retrofuturistic apparati.

A Belle Epoque bordello turned into a themed love hotel.

The storefront of a ramshackle Parisian puppet theater.

The approximate spot where the last Grand Master of the Knights Templar was put to death.

This recessed garden protects thousands of mountain plants by creating its own microclimates.

An immersive projection art installation uses sound, scale, and light to take visitors inside classic works of art.

This Parisian gem is one of the most incredible ethnographic museums in the world.

The narrowest street in Paris.

What looks like a normal building is really a hollow facade hiding a subway vent.

This structure atop a craggy cliff in one of the most beautiful parks in Paris boasts an unbeatable view.

The historic Masonic Lodge in which the first-ever female Mason was initiated.

A museum which takes visitors to the côté obscure of Paris.

The Sun King's military models, saved from the Louvre.

One of the oldest masonic museums in Paris.

An iconic and eccentric bar for "Manouche" Jazz music keeps expanding its space—and its influence.

Beggars were miraculously "cured" of their fake ailments when they returned home to this 17th century Paris slum each night.