A winding, blood-red tunnel of hardened lava navigable by foot.

The most powerful waterfall in all of Europe.

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

This elegant arc of a waterfall marks a religious turning point.

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.

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

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

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

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

A beautiful display of nearly 50 bells crafted with a unique design and distinct sound.

The massive white mound and accompanying water terraces are a striking geological oddity.

The remains of an entire Roman city can be explored in this interactive museum.

Hungarian self-built castle.

A two-way chairlift system between Zugliget and the highest point in the city.

One of the largest barracks of the Austro-Hungarian monarchy's military is now an abandoned ruin.

This Hungarian stilt village is built in a lake that never freezes over due to the power plant that that uses it as a cooling pond.

From Austrians to Nazis to Soviets, this historic Budapest fortress has a history as complex as the city itself.

Built in 1870 at the bridge that connected Buda and Pest, this spectacular incline railway was almost lost forever during World War II.

This Hungarian castle was built out of cardboard and wood until it proved so popular that it got upgraded to stone.

A 19th century artistocrat's mansion, turned into a library, hidden in a modern library.

A small but immensely extravagant palace built by the "Night King."

The Suurhusen church tower in Germany leans over farther than the famous Leaning Tower of Pisa.