A Serbian church lit by chandeliers made of weapons.

This iconic Parisian bookstore doubles as the "Tumbleweed Hotel" for traveling writers.

The curios of pharmacist and collector Henry Wellcome.

Vibrant street art created with mixed media.

A towering spire in the fortress of Kalemegdan honors the victorious armies of Serbia during their struggles against the Ottoman Empire.

Op-art architecture designed for happiness.

The final resting place for the remains of 143 Habsburg royalty.

An ethereal glowing blue ocean cave in Croatia.

The gorgeous library at Trinity College is home to remarkable treasures of Irish identity.

A theatre built to house the rowdy Oxford graduation ceremonies became the stage for a debate about God's existence.

Pilgrimage site for star-crossed lovers.

It houses the remains of a 17th-century version of the Titanic.

These medieval skyscrapers dominate the skyline of this small Tuscan town.

This one-time health resort was used by aristocrats around the world.

The world's most important buildings shrunk to a tiny size.

This massive subterranean fissure is known as the "underground Grand Canyon."

Island wonderland for communist autocrats.

Old-fashioned knowledge and modern engineering create the world's only rotating boatlift.

A church that bred legends, and served as an inspiration for the Da Vinci Code.

The most loyal of little dogs, or a Victorian era publicity stunt?

The final resting place of soldiers' loyal canine companions.

360° views of the city plus five floors of optical illusions and hands-on science.

A cluttered and astounding collection of antiquities and curiosities.

One part local history, 99 parts gruesome haunted house.