An underground city of salt.

Atop this library is one of the most beautiful green spaces in Warsaw.

A spherical "micro-nation" in the heart of Vienna.

Op-art architecture designed for happiness.

The former private quarters and office of Dr. Sigmund Freud now hosts a museum housing the works of the founding father of psychoanalysis.

The Habsburgs' royal collections of art and wonders.

Dine amidst exotic plants at this former royal greenhouse.

This influential Renaissance-era library was once the haunt of kings and monks.

This sweet-toothed bear searching for snacks has been a symbol of Madrid for decades.

This replica Viking village was created for a film that was never shot and is now open to visitors.

Iceland's largest lagoon is home to stunning multi-colored icebergs.

The unique waterfall in Iceland's south features a backdrop of geometric black lava columns.

Strange rock formations tower above the river that snakes through this enchanting Icelandic canyon.

Three columns of volcanic rock shoot out of the ocean.

This black church sits alone among a field of lava rock.

On an island south of Iceland, a large volcanic rock formation resembles an elephant.

This fantastical waterfall is hidden in a cave located in a cracked cliff.

If a glacial river suddenly diving into a sheer chasm via a dramatic, multi-stage waterfall isn't peak Iceland, it's certainly close.

Walk in the footsteps of the gods and straddle two tectonic plates.

This eye-popping Icelandic crater lake is surrounded by red volcanic rock.

Medicinal spa created with the discharge from a geothermal energy plant.

This natural Icelandic fissure allows divers to swim right between two volatile tectonic plates.

The picturesque birthplace of Icelandic democracy is drenched in the blood of its brutal past.

Iceland's tribute to its thankless civil servants.