The oldest (maybe) swimming pool in Iceland is a stunning oasis built into the side of a lush hill.

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

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

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

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

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

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

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

Iceland's largest geothermal mud pool is a little bit haunted and a little bit dangerous.

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

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

An old hill fort covered in over 100,000 crosses is a symbol of Lithuanian nationalism and beliefs.

An empty relic of the Moscow Olympics crumbles away in Estonia's capital.

Around 100,000 bodies are buried below the medieval headstones, many of which mark graves with multiple bodies stacked up to 12 deep.

Macabre astrological automaton clock dating to the late 1400s.

Perhaps the tiniest sculpture in Saint Petersburg is a little bronze finch inspired by a song.

This small chapel is built of human bones and decorated with a golden skeleton.

A favorite with sightseers, this Norwegian funicular provides easy access to a stunning view of Bergen and its environs.

Stay overnight in the world's most sleekly designed rabbit hole, free of charge.

The statue of a legendary giant who carried Christ and shouldered the world's sins.

The widest waterfall in Europe is a natural wonder and one of the only places where fish are caught in the air.

Walk behind a 50-meter-high waterfall.

The burning of this 12th-century church kicked off a campaign of Norwegian Black Metal terror.

Built to ward off Napoleon's army, this city-sized abandoned Russian fort is now perfect for urban exploration.