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

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

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

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

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

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

A history of heat is on display at this unique Austrian museum.

A neo-Gothic mansion now houses a wunderkammer of analog tech that hits on all the senses.

This series of Baroque passageways in Vienna's cultural center mix old architecture with modern art.

Vienna's underworld of tunnels and subterranean rivers made an iconic appearance in a 1949 Orson Welles film.

Apartment complexes built into huge repurposed natural gas tanks.

Vienna's giant wonder wheel had a starring role in one of the greatest noir movies of all time.

Baroque celebration of the end of the Great Plague of Vienna.

This museum promotes informed contraception by documenting its often secret past.

This cubist Vienna church building looks like some sort of alien stonehenge.

Built to give thanks for the passing of a plague epidemic, this cathedral is a one-of-a-kind architectural hybrid.

Op-art architecture designed for happiness.

Legends surround an ancient tree trunk riddled with nails for good luck.

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

Located right outside of Vienna, visitors can take in expansive views of an ethereal forest.

Beautiful Austrian natural history museum with carved ceilings and row after row of ancient taxidermy.

The topiary maze at the Habsburg hunting lodge.

The resting place for anonymous victims of the Danube's dark waters.

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