This tumultuous Icelandic lava field looks so alien European researchers want to use it as a stand-in for Mars.

Moss and stone turn this waterfall into an otherworldly liquid veil.

Dress up like a miner and take a slide into the disco-lit depths of this once foundational salt mine.

Swarovski's museum/theme park is a fake diamond fantasia overlooked by a giant.

A narrow strip of land is home to the tallest migrating dunes in Europe.

The world's greatest slide descends 18 stories from this looping mountaintop viewing platform.

Giant stone letters dedicated to the founder of Armenia's alphabet.

The Bristol Camera Obscura housed in an ancient windmill.

The abandoned funicular tunnel was a secret base for the BBC during World War II.

England's steepest street has such a drastic incline that locals tie their parked cars to lampposts when it gets icy.

The bridges portrayed on EU currency aren't fictional anymore.

More than 5,000 artifacts donated by the people of the city, plus a room entirely devoted to the band U2.

The mummified heart of a saint lives on in this church—after a brief hiatus when it was stolen.

Dublin's "Dead Zoo" serves as a window to Victorian museum design.

A museum that cashes in on its infamous little people while teaching you a thing or two about the Irish fey.

The gorgeous library at Trinity College is home to remarkable treasures of Irish identity.

This strange building looks like a medieval fortress crashed into a 1960s Brutalist office block.

Largest illuminated advertisement sign in the world.

An elegant chandelier hangs over this ancient sewer chamber, now open for concerts and public tours.

A Kyiv-based repository for all manners of discarded curiosities.

A preserved 18th century steel factory.

A Victorian Gothic masterpiece housing a world-class collection of rare books and manuscripts.

These lovely Turkish-styled baths were brought back to life after winning a reality show competition.

This Manchester laundromat is hiding something.