This amazing 15th-century mural remained hidden in plain sight for centuries.

The modest childhood home where the baseball legend and Yankees star learned to hit from both sides of the plate.

This 11th-century structure is one of the oldest churches in Romania.

A giant interactive periodic table with real samples of the elements.

The oldest garden in Prague, once part of an medieval orchard.

A saintly relic hidden in a Prague church basement.

A collection of anatomical samples from one of the first anthropologists to suggest that humans reached North America by crossing the Bering Strait.

The medieval castle built as headquarters for the Pope's secretive Knights Templar.

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

An honorary saint of the people, Maria Adelaide became an incorrupt corpse, the clothes intact, exhaling “a strong scent of roses.”

This oddly shaped church resembles a rocket.

An outsider folly near Madrid.

One of the world's oldest universities houses an incredible collection of anatomical models, mummified body parts, and human bones.

This macabre masterpiece of a mural is one of Francisco Goya's "Black Paintings."

A whimsical brother of the nearby Fallen Angel statue takes the falling part quite literally.

Madrid's romantically ornate crystal palace has been offering shelter to plants and art for over a century.

Colin Stokes "got a bit carried away" and built a castle that looks like something out of Tolkien.

Folklore says this medieval fortress was plopped atop a portal to hell to trap the demons below.

This landmark church concealed a crypt packed with bones that was discovered thanks to the London Blitz.

A hidden treasure in London with a rich medieval history, and the resting place of many luminaries.

A Victorian park cemetery, standing on the site of what was once the Great North Wood.

An small and easily overlooked archaeology museum chock full of Egyptian artifacts.

A naturally mummified 2,000-year-old man.

Dictionary Johnson’s favorite feline.