The former Nazi concentration camp stands as a museum to remember this dark chapter in European history.

An underground city of salt.

Ancient serpentine sacrifice holder that has stood the test of time.

A small etching on the white marble parapet was written in runic script by a Viking mercenary.

A marvel of Byzantine engineering under the streets of Istanbul.

The ancient latrines of the Greeks, in all their public glory.

The Scottish Reformation leader's grave was paved over and is now a parking lot.

Touching this 18th-century Scottish philosopher’s toe allegedly conjures good fortune.

The most loyal of little dogs, or a Victorian era publicity stunt?

A verdant 17th-century-style garden hidden along Edinburgh’s Royal Mile.

A sweet symbol marks the place where torturous executions were once carried out.

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

Wooden sleds have replaced donkeys to cart goods around this utterly charming car-free village.

Hundreds of years ago, this lion-shaped door knocker could help a person accused of a crime find temporary safe haven in Durham Cathedral.

This sculpture marks the spot where one of the greatest Roman rulers was proclaimed emperor.

One of the shortest streets in York has an especially odd name.

The National Railway Museum in York is the largest railway museum in the world, attracting almost 1 million visitors per year.

Follow the original medieval paths that wind through this intriguing section of the city.

Two stone columns flank the grand Venice square, but there were supposed to be three.

The fairy tale castle of the "fairy-tale king."

This 1,300 year old monastery built atop a single rock was once only accessible depending on the whims of the tide.

Perched above the bustling town of Kerak is a sprawling, ruinous castle that has witnessed nearly a millennia of Levantine history.

The world's oldest map of the holy land gives us a fragmented glimpse of the layout of biblical nations.

Known as the "Valley of the Moon," this Jordanian wadi is one of the most amazing desertscapes on Earth.