An underground city beneath Krakow's postwar socialist utopia.

This homeless brass fox tugs at your heartstrings from the foot of a Stockholm bridge.

A hidden bathhouse in one of Stockholm's oldest and busiest neighborhoods is open to anyone who can find it.

Stockholm's last remaining paternoster elevator.

An underwater city for the dead.

Construction of Barcelona's iconic (but controversial) church is expected to be completed in 2026—a century after the death of its architect.

This upscale streetwear store is hidden behind a fake Snapple machine in the back of a deli.

Architectureal fantasy quarter of Rome.

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

Paris' linguistic guide to the international language of, yes, love.

This Venice bookstore has resigned itself to constant flooding by keeping its books in bathtubs and boats.

Stepping away from the glitz of mobsters and casinos to learn about the other history of Vegas.

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

The perfectly preserved underground rooms where Churchill plotted the war against Germany.

The land is full of geologic eye candy, such as otherworldly spires, mushroom-shaped hoodoos, and prehistoric fossils.

A whimsical and twisted animatronic monster tour beneath the streets of Berlin.

Kings Cross Station pays tribute to its role in Britain's best-selling book series.

The only structure left with direct ties to the Salem witchcraft trials of 1692.

The sound of swaying stalks in this stunning grove has been named a governmentally recognized sound.

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

La Monte Young and Marian Zazeela's "Dream House" will immerse you in an ever changing world of sound and light.

One of the few remaining casualties of the London Blitz, this destroyed church has become an enchanting public garden.

A huge musical instrument played by the ocean.

The vast, legendary catacombs hold secrets much stranger than stacked bones.