The doodles of a genius line the walls of a secret room under the Medici Chapel, where they were hidden for nearly 500 years.

Five candy-colored villages on the Italian Riviera.

Giant, pink stuffed rabbit on an Italian mountain.

According to the local folklore, the myriad colors of this lake are the result of a lovelorn wizard's blunder.

Thousands of well-dressed mummies below a monastery.

The astonishing collection of an infamous criminologist.

This small chapel is built of human bones and decorated with a golden skeleton.

A 16th century chapel decorated with bones, skulls, and entire bodies hanging from the wall.

One of the largest Roman settlements in Portugal.

This unreal Portuguese palace looks as though it's made from a pile of different castles.

This eccentrically decorated palace is replete with grottoes, fountains, tunnels, and caves.

A huge cathedral single-handedly constructed by one eccentric monk.

This cemetery features modernist statues as strange as its name.

Partially collapsed lava tube and cave system complete with concert hall, underground pond, and unique albino crabs.

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

Abandoned for decades, trains still pass through the now-restored remains of one of Madrid's first metro stations.

The earliest known map to show America, discovered by accident at a Paris bookshop.

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

Commonly acknowledged as the only public monument to the Devil himself.

One of the few remaining ancient aqueducts described by Frontinus as 'the most solemn testimony of the Empire.'

Mountain where Jesus was first tempted by the Devil.

A landscape decorated with enormous skull sculptures.

This Navarrese cave's history of witchcraft and pagan ritual is not just embraced, but recreated each year.

Hundreds of stone stairs and a winding medieval bridge connect this haunting Spanish island to the mainland.