At the very tippity-top of Europe is a cliff from which you can view the midnight sun.

The convergence of two currents makes this a surprisingly pleasant getaway in the Arctic Circle.

This "preacher's pulpit" once used for pagan ritual, is home to a new, and dangerous ritual.

This giant boulder is pinched over a 1000-meter abyss by two mountains.

Walk 2,300 feet above the ground on the "Troll's Tongue."

This 13th century Gothic brick castle is the largest in the world by surface area.

This sprawling concrete suburb of Kraków was designed by the Soviet Union as the model proletarian city.

This 700-year-old structure is one of the most unique architectural and historic monuments in Gdańsk.

The site of the first battle of World War II.

This Polish cave has housed a dragon, a brothel, and an enduring legend.

An underground city of salt.

A 19th-century mansion houses the largest collection of gin in the European Union.

Perhaps the most spectacular grotto along the Algarve coastline.

This giant sculpture made of trash is a critique of society's wastefulness.

Building owners can take out tiles for free at this repository for historic building materials.

Located in the thermoelectric factory that once powered the entire city, this Portuguese museum is shockingly fascinating.

In Portugal, a secluded stretch of untouched natural beauty hides at the bottom of a steep hill.

An abandoned mine now resembles a post-apocalyptic landscape of derelict buildings and blood-red pools of water.

This gaping hole in the middle of a remote mountain lake looks like a portal to another dimension.

Houses are tucked between, on, and underneath giant boulders.

This eccentrically decorated palace is replete with grottoes, fountains, tunnels, and caves.

From Nazi chemicals to the CIA, this architectural marvel has played a fascinating role in German history.

An officers prison camp believed to be impregnable by the Germans saw over 30 successful escapes.

A subterranean display of public art and architecture.