A popular swimming hole that hides one of America's most deadly diving spots.

An emerald-green grotto just a short trip from Austin.

This simple frog painting created by musician Daniel Johnston embodies the spirit of Austin.

A synth musician's paradise at the heart of a community responsible for the soundtrack to 'Stranger Things.'

Decades before the scandal, this staircase on the river was a literal "water gate."

Tucked away in the Leiden city hall are a group of works by famed artist MC Escher.

Nestled in the hills of Tuscany are gorgeous, multicolored hot springs.

Rainbow-hued in the summer and crystalline in the winter, this salty lake has inspired battles, temples, and plenty of awe.

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

A natural wonder in south Denmark.

A true Valhalla for cactus and succulent lovers.

A former plague hospital turned medical museum.

This centuries-old gothic monster has been converted into a sprawling, glossy bookstore.

Hidden within a Netherlands crater is a stone bed that lets those who lie in it see the sky as a curved surface.

Peek through a transparent pyramid and drink in the mountain made of books.

Inspired by "The Starry Night" this Dutch bike path turns into a glowing work of art each night.

The attic of a four-century-old canal house hides a clandestine church.

A Dutch passageway's artistic, aquatic-themed makeover pays tribute to the capital city's famed waterways.

This gorgeous reading room houses the oldest and largest art history library in the Netherlands.

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

Established in 1638 to battle the Black Death, Hortus Botanicus Amsterdam is a treasure trove of rare flora.

This semi-secret garden in south Seattle emulates a traditional Japanese garden using the plants of the Pacific Northwest.

This 19th-century church is now a popular roller rink.

A favorite haunt of dinosaur loving children and hallucinogen loving hippies alike.