This fort down the Potomac from Washington, D.C. was once the only defensive fort protecting the capital.

During the Industrial Revolution this “Temple of Invention” was full of intricate miniature machines and gadgets.

The whimsical twist of this spire was either caused by the Devil, an unexpected virgin, or lead.

An small and easily overlooked archaeology museum chock full of Egyptian artifacts.

A plaque hangs near the execution place of the Scottish Independence leader famously depicted in "Braveheart."

You'd never know the houses at 23-24 Leinster Gardens were fakes—until you see the train tracks on the other side.

Twenty-seven massive radio antennas on the high plains of New Mexico search for life on other planets.

A museum dedicated to the alleged Roswell Incident.

Wedding chapel's mysterious spiral staircase said to be miraculously constructed.

A sprawling collection of over 106,000 toys from around the world.

The site of Billy the Kid’s most famous escape and the end to the Lincoln County War.

The first tunnel to be dug beneath a river, repurposed as an art and museum space.

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

A much-maligned monument to teetotalism.

This silent sentry in the crypt below a large Gothic cathedral is often knee-deep in water.

The last moments of the ill-fated Pompeiians, frozen forever in plaster.

This tipsy office building in downtown Prague was originally called “Fred and Ginger.”

This elaborate towering structure was once famed for its revolutionary height.

A medieval replica of King Arthur's legendary table, the Round Table hanging in Winchester Castle was decorated by Henry VIII.

A collection of comics, graphic novels, animation and caricatures devoted to exploring this often overlooked art form.

A treasure trove of astronomical, mathematical, and scientific instruments at Cambridge University.

A turn of the century building boasting some of the most beautiful art nouveau architecture in Prague.

Home to items never before seen by the public.

Several plaster noses are hidden in plain sight around London's Soho neighborhood.