The idyllic island where the philosopher Jean-Jacques Rousseau spent “the happiest time of his life.”

Enormous, fluffy dogs frolic around this museum dedicated to a legendary Saint Bernard.

This 170-year-old Swiss guesthouse built into the side of a mountain is best accessed by a cable car.

This architecturally eclectic fortress witnessed centuries of bloody turmoil, including the massacre of its ruling clan.

Take respite inside this jaw-dropping church while climbing the volcano where Georgia's Prometheus was once chained.

This astonishingly geometric cave has inspired everyone from Jules Verne to Pink Floyd.

An otherworldly alpine pasture with its own unique microculture that recalls Middle Earth.

This one-time health resort was used by aristocrats around the world.

Museum deep in the catacombs of St. Michael the Archangel Church is explored by touch, sound, and smell.

A memorial to the murdered Jews of Kaunas.

A narrow strip of land is home to the tallest migrating dunes in Europe.

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

The frozen bubbles that form on the icy surface of this Canadian lake contain enough methane to create a small explosion.

This tiny square mile of Canadian sand was once considered the world's smallest desert.

Ice roads, deep holes and 3,500 pounds of diamonds.

These hellish-looking cliffs in the Canadian Arctic have been burning for centuries.

The third-largest island in Canada is one of the remotest places on Earth.

These former Nazi anti-aircraft towers offer a singular view of the north of Berlin in the summer, and a sanctuary for bats in winter.

The world's first clock to use set theory as a measure of time required the invention of a new light bulb just to maintain its obtuse measurements.