The tunnel's elegant proportions keep you snug with no claustrophobia freak-out.

A bust of Franz Kafka spins in pieces, reflecting the writer's inner torment.

A Jenga-style cylindrical tower of books that appears to go on forever.

A Pythagorean funhouse that tries, successfully, to prove that math is the coolest thing ever.

Fine dining in the bizarre world of Lewis Carroll.

A miniature rainforest is growing inside of a Midtown Manhattan office building.

Elevated freight railway turned wildly successful urban park.

New York's oldest magic store.

This restaurant was removed from the famed sister ship of the Titanic and placed within a hotel.

This iconic 1,000-year-old medieval castle is a favorite of the film industry, most notably as the location for Hogwarts in Harry Potter.

The sign at the garden gate reads: "These Plants Can Kill."

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

An enormous, inside-out glass globe built in 1935.

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

The fairy tale castle of the "fairy-tale king."

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

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

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

This jaw-dropping 19th-century bridge uses its reflection to form what appears to be a perfect circle.

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

An exquisite tunnel of cascading flowers.

The great Danube river starts here.