A beautiful deserted greenhouse in the middle of a park.

The busy transport hub is home to the tallest airport slide in the world.

This unique temple complex remains off the typical tourist trail.

A colossal floating restaurant built to look like a ancient Chinese imperial palace.

This ancient Greek place of assembly and marketplace is being revealed layer by layer below the modern Athens cityscape.

A 2,000-year-old computer demonstrates remarkable engineering and astronomical precision.

From cartoon characters to tiny tanks, a guerilla sculptor's little bronze statues are hidden throughout the city of Budapest.

Possibly the world's largest hourglass only needs to be reset every New Year's Eve.

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

The metal leaves on this tree are engraved with the names of Holocaust victims.

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

The geographical center of Budapest is marked with a 10-foot-tall stylized zero.

This statue of a falling man commemorates a teenage martyr of the Hungarian Revolution.

Some of the greatest minds in the history of Hungarian art and science converged in this café.

A two-way chairlift system between Zugliget and the highest point in the city.

Uh, pardon me, ma'am, but I couldn't help noticing that there's a Columbo statue in the middle of Budapest.

Tucked away near more famous landmarks lies a statue meant to symbolize the confluence and continuing development of human culture.

The abandoned "Red Star Train Graveyard" is the final rusting place for precious artifacts of train history.

Built in 1870 at the bridge that connected Buda and Pest, this spectacular incline railway was almost lost forever during World War II.

Atop this library is one of the most beautiful green spaces in Warsaw.

A statue commemorating a Polish dog who took his role as man's best friend very seriously.

This enormous 32-foot painting depicts Poland's greatest medieval battle in glorious detail.

Dubbed "Wistom" by locals, this abandoned factory is an urban explorer's dream.

Legend says this is actually a heartbroken prince waiting for his true love's kiss.