27-room home built with the fortune of a sugar magnate.

For more than 70 years, this small shop has been a go-to for Kolkata's fountain pen connoisseurs and collectors.

Abandoned bridge hidden deep in the San Gabriel Mountains.

Once the "Eighth Wonder of the World," this iron railroad bridge was decimated by a tornado.

The oldest of Venice's plague quarantine stations, designed to keep the medieval city safe from disease.

A Swedish town came up with an out-of-the-box way to eliminate the bloodthirsty insects.

An incredibly durable timepiece glows beneath shoppers' feet.

The final resting place of the poets Shelley and Keats.

Sitting on an Italian hilltop is this surreal fortress built by the mad inventor of electrohomeopathy.

Venice's "Island of the Mad."

As can be expected from a centuries old church built in a canal city, the undercroft of this house of worship is beautifully flooded.

2300-year-old Roman road connecting the empire.

Stalactites and stalagmites in a beautifully lit cave.

The underground sanctuary of a mysterious ancient cult.

Pompeii's less famous neighbor is still revealing her secrets.

A submerged archeological park still holds the wonders of a Roman Sodom.

Hundreds of lucky felines haunt the ruins where Caesar was murdered.

A 16th-century horror show built in a lovely Italian garden.

An Italian crevasse filled with abandoned buildings gives visitors a look at the world without humans.

The crypts of Capuchin friars decorated with the bones of over 4,000 friars, including an entire "crypt of pelvises."

This futuristic observatory at the top of the Pyrénées offers unrivaled views.

This modern French ossuary contains the jumbled bones of 130,000 WWI soldiers.

The famous winding walk at Chartres is surrounded in mystery and myth.

For hundreds of years, automatons moving to metallic music have been marking the passage of time.