A toxic ghost town sitting atop a massive coal fire.

A tiny piece of the Moon is embedded in this stained glass masterpiece.

The sci-fi villain is a little-known inhabitant of the U.S. capital's largest cathedral.

At 207 feet, one of the world's longest continuous escalators.

Venice's island of the dead.

Go inside to really appreciate this 500-year-old technological masterpiece.

2300-year-old Roman road connecting the empire.

Charles Dickens was not a fan of the ghastly wall dressings in this 6th century church.

A Nesting Doll of Churches.

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

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

The Pope’s secret escape route.

Ship-sized kinetic sculptural fantasy.

The gorgeous library at Trinity College is home to remarkable treasures of Irish identity.

The mummified heart of a saint lives on in this church—after a brief hiatus when it was stolen.

An Irish church where an 800-year-old mummy is reaching out of his coffin as if to shake hands.

The ancient tomb acts as a calendar that keeps perfect time.

A waterfall 600 ft. inside a mountain, once the bane of gold miners, is now a spectacle of nature.

The world's largest mountain carving could fit all of Mount Rushmore inside it many times over.

The granddaddy of all tourist traps, built on ice water, jackalopes, and a giant dinosaur.

One man's quest to save his town with a trail of record-breaking sculptures.

The world's largest Holstein cow.

A rim-made reptile in North Dakota.

A monument to the center of the North American continent may be off by a few miles.