Stalactites and stalagmites in a beautifully lit cave.

Crushed coral and crystals give the sand its signature coloration.

Marvel at this immense work of art that greets arrivals to the city.

These secluded and abandoned anti-aircraft defenses have become one the most scenic viewpoints in Barcelona.

Oldest surviving example of a Dutch saltbox frame house in America.

An ancient octagonal weather station named for the eight Greek gods of wind.

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

The history of the tea trade is told in bas-relief on this historic pair of Boston doors.

Mrs. Mallard and her brood are a beloved fixture in Boston Public Garden.

This stunning concert hall has become a symbol of Iceland's national recovery.

Giant WWII fortresses that fired 8,000 rounds a minute, now home to thousands of pigeons.

Unsurprisingly, Holland is home to one of the most magnificent flower gardens in the world.

This contentious squat has stood through fire, violence, and government intervention as a hotbed of leftist protest.

An abandoned village that resides along the mountains of the Aosta Valley.

Stuck in the arcade of Casa Isolani are three arrows of mysterious origins.

Legend has it this fountain built to symbolize the Pope’s power hides a strange secret concerning Neptune's manliness.

A fairytale-like medieval church perched atop a rocky cliff on Italy's "Coast of the Gods."

Geometry and mystery come together in an epic show of octagonal masonry.

Macabre symbols of death and mummies on display set the tone of this Italian purgatory church.

Southern Italy's spinning top village.

The sunlight passing through the opening of this huge cave system creates a magical effect.

One of the world's oldest working clocks is curiously missing the Zodiac sign of Libra.

Built to repay the sins of the father, this church is home to one of the most valuable works of Western art.

Featuring the last fully walkable parapet walkway in Europe.