This abandoned coliseum was intended to be a grand Nazi rallying ground before it was halted at the end of the war.

A castle from the Holy Roman Empire that hosts traveling youth... in its stables.

A museum that chronicles the history of the Nuremberg Trials for Nazi war criminals in the building where the trials were once held.

The severed head of a 17th-century Irish martyr lies within an intricate golden shrine.

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

This center tells the story of one of the most famous battles in Irish history.

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

An ancient Roman theatre restored to its former glory in the Spanish city of Cartegena.

A church of bones, decorated with 40,000 human skeletons.

An enormous and lavish Gothic church in Czechia.

Despite attempts by local police to discourage it, Beatles-inspired graffiti has been a means for artists to air grievances for decades.

The first museum in the world devoted to sexual gadgetry.

Macabre astrological automaton clock dating to the late 1400s.

Construction of Barcelona's iconic (but controversial) church is expected to be completed in 2026—a century after the death of its architect.

The ship built to ferry passengers and goods to the doomed Titanic is now the last remaining White Star Line vessel.

Eighty million natural history specimens call this gargantuan museum home.

A hugely vast Irish landscape of barren rock that stretches for miles.

This is the largest cemetery in Ireland and the first cemetery museum in the world.

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

Thousands of coffin-like pillars make up this controversial Holocaust memorial.

An imperial church bombed to ruins during WWII now stands as a jagged memorial.

The site of a concentration camp where inmates were made to take part in one of the largest counterfeiting operations in history is now hauntingly empty.

Daily jousts and dancing barrel makers in Munich's mechanical clock.

The prototype for all Nazi concentration camps.