This Neolithic passage tomb forms part of a World Heritage Site.

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

Dublin's "Dead Zoo" serves as a window to Victorian museum design.

The block of aged dairy is probably still edible after 2,300 years in a peat bog.

This permanent collection of preserved bodies taken from Irish bogs is one of the leading authorities on such morbid mummies.

This extinct volcano rises above Edinburgh and is special for its panoramic views over the city.

Sprawled across the Great Hall ceiling are various constellations and images relating to the zodiac.

This collection of Neolithic monuments make up one of The U.K.'s richest archeological landscapes.

The ruins of this 19th-century Scottish Baronial mansion reflect the architectural heritage and history of Scotland's aristocracy.

Looking strangely like Rome's Colosseum, this unfinished tower has dominated the skyline for over 100 years.

Inside this art museum resides one of Glasgow's most famous musical instruments.

Royals, rebels, and artists have all conversed at this grand 19th-century Viennese coffee house.

A museum of Czech puppetry and wine in an allegedly haunted 14th-century stone house.

Be(w)ar(e) the moat around this historic Czech castle.

Two stunning 17th-century libraries and a cabinet of curiosities.

Macabre astrological automaton clock dating to the late 1400s.

The bones of the Biblical Magi traveled to Constantinople and Milan before landing in their current home inside an elaborate golden reliquary in the Cologne Cathedral.

The largest bell in the world has been swinging high above a Cologne cathedral for almost a century.

Thousands of tourists and residents in Cologne affix "love padlocks" on the Hohenzollernbrücke Bridge to symbolize their affections.

This gorgeous reading room houses the oldest and largest art history library in the Netherlands.

The attic of a four-century-old canal house hides a clandestine church.

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

A Dutch passageway's artistic, aquatic-themed makeover pays tribute to the capital city's famed waterways.

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