An underground city of salt.

A curious cave church carved into the face of a cliff.

Mortarless walls that stretch for miles are a lovely solution for creating grazing land in the harsh terrain of the Aran Islands.

A proud bronze billy stands as an eternal symbol of Ireland's oldest festival, where a goat is made king.

The oldest licensed distillery in Ireland.

Berlin's old airport.

This short bridge is the only thing connecting a tiny Irish island to the mainland.

Go inside to really appreciate this 500-year-old technological masterpiece.

What started as a tongue-in-cheek shrine is now a full-blown museum celebrating "The Hoff" and his longtime love affair with Berlin.

A man-made island in scenic San Francisco Bay.

This bridge was constructed from the rubble of the infamous Bastille.

Art from the latest counter-culture; kids who dye their hair blue and believe the future will be a post-apocalyptic water world.

A series of abstract, silly sculptures represent the works of a great modern classical composer.

The spiral staircase hidden inside this giant Parisian column was likely built for Catherine de Medici's astrologer.

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

This former KGB building is now a museum memorializing the people who suffered during the Soviet regime.

The first museum dedicated to exploring humanity's cultural relationship with the celestial world.

Legend has it that Napoleon Bonaparte fell in love with this Gothic church.

Folky pharmaceuticals abound in this medicinal reliquary.

While this monument tile is shrouded in mystery it also marks the end of the longest ever human chain.

Travelers who fall victim to this mermaid's charms are destined to stay in Užupis forever.

A tiny traditional village keeps an ancient method of beekeeping alive.

Just another terrifying garden filled with hundreds of endlessly smiling doll people.

A stone marker and sculpture in the city of Riga stake a claim for the very first community Christmas tree.