One of Ireland's most infamous prisons for rebels including men, women and children.

This Roman relic was discovered in Scotland by a mudlarking ferryman.

This otherwise ordinary close on the Royal Mile constituted the end of the world for Edinburgh’s poorest residents.

Overlooked by many, the two famous Scottish warriors guard the main gate of Edinburgh Castle.

A statue in the heart of Edinburgh honors a bear that served in the Polish military during World War II.

Long abandoned underground complex to keep royals safe from a nuclear war that never came.

17th century streets hidden under Edinburgh were once a breeding ground for the black death.

Hear the quietest sound from across the dome.

Wedged between two buildings at the Great Ormond Street Hospital is this secret music installation.

This London pub hides a peculiar secret: a recreation of the rooms shared at 221b Baker Street by Sherlock Holmes and Dr. Watson.

The popularity of Sherlock Holmes led to the creation of his fictional address, turning the orderly London street numbers askew.

Kings Cross Station pays tribute to its role in Britain's best-selling book series.

This hill made entirely of ancient Roman jars was simply a garbage dump to the people of the time.

Installed in an act of one-upsmanship, the annual sundial in this church is also a symbolic victory for the Gregorian calendar.

The yawning maw of this pagan visage is said to bite off the hands of liars.

Indents in the pavement are all that remain from a grisly death machine in Paris.

An "inside out" building in the historical center of Paris, featuring Europe’s largest modern art museum.

High atop the Eiffel Tower is a small apartment built exclusively to entertain the science elite and make the rest of Paris jealous.

The vast, legendary catacombs hold secrets much stranger than stacked bones.

The oldest bar in Missouri is hidden within a limestone brewery cellar more than 50 feet underground.

This art deco masterpiece was once a miracle spring mecca but is now simply a government office building.

A tiny racehorse graveyard in the middle of a quiet Kansas City suburb.

This Italianate Villa-style castle is pretty to look at, just keep off the private property.

The first car-centric shopping plaza in the U.S. brought a little bit of Spain to downtown Kansas City.