Once the home of a hermetic monk, this cave now houses a small church.

A triumphant marble and bronze fountain depicting a 15th-century Hungarian king and his hunting party.

At the right time of day, sunlight floods through the roof of this cave and illuminates the small pavilion hidden within.

This sculpture honors the man who was known as the "Righteous Among the Nations."

The world's oldest individual clonal tree looks like a wimp despite standing tall for 9,550 years.

A marvel of Byzantine engineering under the streets of Istanbul.

A meow-velous tribute to a beloved street cat, made famous on the internet.

On Gellért Hill, this statue depicts the tragic tale of lovers divided by the Danube.

Sweden's "good old days" painstakingly re-created in a model village.

Stockholm's deepest subway station is also a stunning ecological wonder.

The library's graceful rotunda is like a bibliophile's temple.

Stockholm's decidedly unique public transit system has doubled as the world's longest art gallery for decades.

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

A flight of this "ghost staircase" has 40 steps on the way up, but only 39 steps on the way down.

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

A public urinal so pretty, it was declared a national monument.

For six months of the year, three giant mirrors direct a pool of sunshine onto this otherwise occluded town.

Europe's only museum solely dedicated to the history of whaling still has a fully-functioning whaling ship.

Thousands of miniature bronze sculptures have taken over this city square creating a unique art installation.

An immersive environment that is part haunted house, part choose-your-own-adventure, and part jungle gym.

This beautiful 16th-century necropolis marks an astonishing feat in heritage conservation.

No need to strap in for a "ride" on this walkable roller coaster.

Venture into the hideout of one of Hong Kong's legendary pirates.

It should come as no surprise that the best view of the Hollywood sign is from Batman's lair.