The blood-soaked ruins of the castle where the murderous Blood Countess was walled in alive.

The deepest sinkhole in Central Europe comes with a grisly tale and an unusual nickname: “The Stepmother Abyss.”

The world's greatest slide descends 18 stories from this looping mountaintop viewing platform.

This fortress was designed to prevent a Nazi invasion but was never used.

Underneath this small church are 15,000 bones, arranged by an obsessive academic.

The 14th-century ruins are said to contain healing powers.

The mystery of the Putim Ossuary involves a tricorn hat.

These 17th-century mummies are no longer naturally preserved, but remain on display today.

A Cold War secret surveillance tower used to spy on radio communications.

This magnificent castle grew from a small Moorish fortress, and reportedly inspired two iconic Disney castles.

This castle has links to Portugal’s founding and struggles for independence.

A hidden three-foot-wide house separates these two regal churches.

One of the most beautiful bookstores in the world hides a neo-Gothic interior behind an art nouveau facade.

This restored Portuguese cafe may well be the most beautiful place in the world to grab a Big Mac.

Elaborate tile work in this railway station tells the story of Portugal.

The stunning interior of this Gothic church is covered in ornate gold details.

Built to ward off Napoleon's army, this city-sized abandoned Russian fort is now perfect for urban exploration.

"There's nothing there," and other lies the KGB told us.

Morocco's largest Jewish cemetery.

It took 40 years to build this Eden-like garden in Marrakech, later restored by Yves Saint-Laurent.

This amazing oasis of art and plants is hidden on the outskirts of Marrakesh.

This vast masterpiece of Moroccan architecture spreads across 20 acres.

The remnants of two World's Fairs are here, complete with a 12-story globe, a mini-Manhattan, and a UFO-shaped pavilion.

Commonly referred to as the most photographed Victorian home in the United States.