An Art Nouveau gem hides beneath the layers of city grime obscuring this once-magnificent building.

Ancient serpentine sacrifice holder that has stood the test of time.

This remarkably well-preserved Egyptian plinth is pretty well traveled for a giant piece of stone.

A fountain standing as a testament to a doomed alliance.

Five sultans and their families rest in eternal splendor, teeming with overlooked beauty and drama.

A marvel of Byzantine engineering under the streets of Istanbul.

The ancient necropolis houses the immense rock-cut tombs of four Persian kings.

The 700-year-old fortress was the site of Count Orlok's castle in "Nosferatu."

The hottest, driest, and most scenic desert on Earth.

This abandoned secret city is a crumbling wonderland of Soviet ruins.

Dark, eerie exhibits make for a surreal exploration of the subconscious.

Now harmless, this looming post struck fear into the heart of medieval troublemakers.

The gorgeous entrances into the city's underbelly look more like grand halls than subway stops.

The centuries-old crosses "growing" in the cemetery are steeped in local lore and are believed to have healing powers.

Colorful concentric circles honor a small Croatian town's supposed spot at the nucleus of it all.

Large, airy hallways hide within an impenetrable fortress that beckons urban explorers.

A Swiss board game museum housed inside a picture-perfect castle.

A constellation of golden cobblestones shows the names of local children born under a full moon.

The labyrinthine home of the National Archives of Estonia is an experimental blend of architecture, art, and history.

Artwork tucked within the trees greets visitors with surreal sonic experiences.

Trimmed trees grow alongside the graves like topiary tombstones.

A city block packed with whimsical sculptures that seem to be plucked from a tiled fantasy world.

The world's newest astronomical clock is also its most accurate.

Its front wall is striped with a menagerie of fantastic beasts and magnificent monsters.