A series of modernist treehouse hotel rooms grace the outskirts of an Arctic forest.

The library's graceful rotunda is like a bibliophile's temple.

A hidden bathhouse in one of Stockholm's oldest and busiest neighborhoods is open to anyone who can find it.

Sweden's first nuclear reactor, R1, can be visited 25 meters underground.

The world's first zoo for microbes collecting the horrible and wonderful things living on and around us.

Museum preserving torture methods from the past.

This collection of unique liquids allows visitors to wander the waters of Iceland's glaciers.

A giant red chair bolted to a rock on a remote mossy hillside in Iceland.

A sulfuric martian landscape that looks far better than it smells.

The oldest steel ship in Iceland has been beached for years and is now a rusting ruin.

Travel deep inside of Europe's second largest glacier in the world's largest man-made ice cave.

This tiny museum's sizable collection is jammed into a former underground public toilet.

A trio of hidden hot tubs takes advantage of Iceland's natural geothermal vents.

This wrecked airplane has been sitting on a black sand beach since the 1970s.

This hobbit-y little hot spring may be the oldest spring used by humans in all of Iceland.

A little-visited waterfall in an otherworldly landscape.

Every summer local children form "pysja patrols" to save young birds that have wandered from their nests.

These ominous lava formations were said to be an entrance to the netherworld so of course they inspired a famous metal band.

This valley of hot springs and boiling mud pots is home to the record-holding "Geysir," which originated the English word.

An encyclopedic collection of mammal penises.

Iceland's "Smoky Valley" is a beautiful river that is shrouded in a constant cover of steam clouds.

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

One of the tallest buildings in Iceland, and perhaps, the most visually impressive.

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