One of the now-less-hidden floral gems of the "Emerald Necklace."

Macabre headstones carved with winged skulls, dancing skeletons, and pithy reminders of impending death.

A beautiful Victorian-era cemetery, complete with a miniature village.

The vast, legendary catacombs hold secrets much stranger than stacked bones.

This jaw-dropping 19th-century bridge uses its reflection to form what appears to be a perfect circle.

In the fictional world of Kcymaerxthaere, celestial wonders marked a portal to a powerful route of travel at this site in Madrid, Spain.

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

The birthplace of an eccentric alchemist and possible inspiration for the fictional reanimator of monsters.

A chain of 16 wondrous lakes formed as a result of the gradual dissolution of soluble layers of bedrock.

Numerous impressive carvings are embedded in the trees lining this street in Marrakech.

Mosaics, storks, and brothels—this ancient city has it all.

An awe-inspiring mosque in Morocco with one of the tallest minarets in the world.

Castle and secret tunnel withstood a siege until its owner was killed by the Holy Roman Empire, while sitting on the toilet.

Yugoslavia's biggest underground airport lies in ruins.

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

This crumbling Portuguese ruin overlooks the populace it once ruled.

Two stunning 17th-century libraries and a cabinet of curiosities.