Tucked away amidst some of the most famous addresses in the world is New York’s only fraction of a street.

This castle-like building in Manhattan helped destigmatize cancer in the 19th century.

The 28-foot granite map plots the locations of 40 theaters in New York City.

A pedestrian island in the middle of world-famous Times Square emits a strange (and purposeful) humming noise.

Fake subway tiles were installed to cover a design that resembled the Confederate flag—it's unclear if the resemblance was intentional.

This historic address is home to the beloved ball and is an almost totally empty building among the most expensive real estate in the world.

This unassuming stone commemorates a condiment factory gone up in smoke.

This former Masonic hall has been turned into an art project that uses even more metaphysical iconography.

Cryptic messages embedded in the New York City sidewalk.

Stunningly detailed mosaics in a New York subway station bring life to the Weimaraners of artist William Wegman's work—and to thousands of commutes.

Some 80,000 Delft Blue tiles line the inside of this Amsterdam walkway.

Tucked in the back of a flower shop, its collection details the fascinating history of the Netherlands's iconic symbol.

The former headquarters of history's oldest megacorporation.

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

In the days before house numbers, these colorful signs held clues about various buildings' purposes.

A thought-provoking outdoor art installation sits in the seat of German law.

The last municipal pneumatic post system in the world was in operation for over 100 years, and may run again.

This spooky statue sits outside a famous Prague theater.

A crucified and bearded female saint.

Two stunning 17th-century libraries and a cabinet of curiosities.

The oldest garden in Prague, once part of an medieval orchard.

Looming communist pillar with a Czech twist.

A 400-year-old mummified arm dangles from the ceiling of St. James the Greater, serving as a warning to thieves.

A half-buried vehicle in Prague's is the latest iteration in a long-running piece by Czech artist David Černý.