According to tradition this is the oldest church in Venice, but its actual age is a mystery.

Heralded as the world's first theater, these ruins are often overlooked as they reside in the shadows of the Acropolis.

A preserved portion of an ancient Athens barrier is displayed in a hotel basement.

A Byzantine-era church hidden in a wooded area below the Acropolis.

This ancient Greek place of assembly and marketplace is being revealed layer by layer below the modern Athens cityscape.

The hallucinogenic center of the ancient world.

Monasteries on rock pillars, once accessible only by frayed ropes.

This fortress dates back to the 6th century and is also the site of a controversial abandoned restoration project.

This one-time health resort was used by aristocrats around the world.

This historic cemetery was inaccessible for several years due to dozens of land mines.

This enormous abstract sculpture is part jungle gym, part elaborate noise-making machine.

The place where World War I began.

This historic timepiece is thought to be the only public clock in the world that keeps lunar time.

Oriental bazaar in the heart of Sarajevo.

This Slovak bridge is known both for its connection to a national uprising and its UFO-shaped eatery.

"Medieval" castle built in the mid-20th century by one family.

The abandoned military base looks like a post-apocalyptic wasteland.

Hungarian self-built castle.

This elaborately decorated, fairytale-like Romanian royal palace is one of the most striking castles in Europe.

The possible imprisonment of Vlad the Impaler here earned the medieval castle its nickname, "Dracula's Castle."

Once an opulent Art Nouveau hotspot, the Constanța Casino is one of Romania's most beautiful abandoned buildings.

The beautiful 16th-century stepwell lies in the shadow of a famous fortress.

This opulent 16th-century Maharaja’s palace is a unique mix of Hindu and Muslim designs.

More than half of this Indian palace is drowned but it looks all the more spectacular for it.