Amid the bustle and noise of the Financial District hides a secluded garden oasis above the city streets.

Manhattan’s Battery Park has a whimsical carousel full of spinning, glowing fish.

This abandoned subway station beneath the Waldorf-Astoria hotel is allegedly used to secretly transport presidents.

Dodge prohibitionists and slide through the telephone booth in Crif Dogs.

This beautiful building in the heart of Manhattan's Financial District was empty for decades.

A treasure trove of artifacts, books, and artwork from the "golden age" of exploration.

Tucked in the back of this amazing antique store is an important piece of medical history.

A crumbling hospital from the 1850s on Roosevelt Island.

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

A beautiful and abandoned New York subway station from 1904, complete with chandelier.

A terrific purveyor of natural history objects and curios.

A tiny museum housed in a New York freight elevator specializes in the "overlooked, dismissed, or ignored."

One of the world’s smallest bars, just 13 square feet, is brimming with speakeasy flair.

A stately palace has been converted into the world's largest cannabis museum.

Barcelona's historic 19th-century sewers, whose foundations were laid in medieval times, are open to the public for exploring.

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

This conical hill was built as a testing ground for an engineer known as the Glider King.

A museum dedicated to a Cold War era sausage.

A tree-like building perches on its trunk in the Steglitz neighborhood of Berlin.

This classic restaurant features a gorgeous mirror-clad room.

A state-of-the-art medical facility from the Imperial era is now a derelict ruin.

An abandoned NSA listening post on Berlin's "Devil's Mountain."

A tour of underground Berlin takes you through WWII air raid shelters and tunnels used to smuggle people out of East Germany.

An eerie, derelict amusement park in Berlin.