One of London's lost rivers runs through a pipe over the tracks of this subway station.

Also known as Rye Castle, this 13th-century fortification later became a prison and held one of Rye's most famous criminals.

This centuries-old hotel hides a network of secret cellars and passages once used by smugglers.

Two gilded cherubs perched on a church bell tower have been reminding visitors of the finitude of life since 1760.

An ancient water supply dating back almost 500 years can still be found standing in East Sussex.

The world's largest collection of ship figureheads includes figures from legends and history alike, from Sir Lancelot to Abraham Lincoln.

This region of Slovakia boasts some of the most plentiful opal mines in the world.

In an area known in Bratislava’s postal history, this sculpture sits equipped with a functional postbox.

The site is dedicated to an investigative journalist whose murder triggered a political uproar that changed Slovakia forever.

Brass plaques embedded in pavement preserve the memories of those who lost their lives at the hands of Nazis during World War II.

Often mistaken as a medieval Gothic monument, this unique cornerstone only dates back to the 1980s.

Dedicated to a synagogue that was destroyed after having survived World War II.

A sculpture of the beloved author surrounded by characters from his fairy tales.

No one knows the origin of this creepy little stone man with an oversized phallus.

Launched by Napoleon's soldiers more than 200 years ago, a cannonball remains embedded in the tower wall.

An ode to a soldier who came to town, fell in love, then began making his own sparkling wine.

A sculpture of a beloved local figure, who tipped his top hat to everyone he passed on the streets of Bratislava.

This Slovakian statue of an emerging sewer worker might just be a bronze peeping tom.

According to the local legend, these boys and ducks were turned to stone by an angered water goblin.

Too much gossip or just missing curfew could land you in here for a couple of days.

A perfectly preserved hill village where the buildings are painted like white lace.

This statue of one of the engineers who created the London Underground hides a ventilation shaft for the tube lines that run under the street.

One of London’s rare Tudor-era buildings is a fate-defying gatehouse for a church.

This building contains a door only used by members of the royal family.