The commemorative stone column conceals a secret laboratory.

London's smallest police station is barely the size of a phone booth.

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.

The Bristol Camera Obscura housed in an ancient windmill.

Six ravens are kept captive (but well-fed) at the Tower of London to prevent the fall of the Crown.

The watery entrance for condemned prisoners heading to the Tower of London is still visible along the Thames.

These wire animal sculptures commemorate the exotic inhabitants that once called the Tower of London home.

Richard III supposedly disposed of his nephews' bodies here in an effort to seal his claim to the throne.

London's only public statue of the much-married monarch adorns the gate to St Bartholomew’s Hospital.

J.R.R Tolkien, C.S. Lewis, and other "Inklings" met at the Oxford pub to discuss the now legendary fantasy stories they were writing.

A giant sculpture of the legendary "Salmon of Knowledge" celebrates the return of fish to Belfast's River Lagan.

The last Victorian market in Belfast.

The real life town from the Pied Piper of Hamelin has a mechanical puppet show that retells the famous story many times a day.

An expansive complex of subterranean tunnels is all that remains of one of Europe's most formidable medieval fortresses.

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

This futuristic German television spire is actually the world's largest digital clock.

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

The prototype for all Nazi concentration camps.

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

A contemporary art installation housed within a Gothic cathedral.

An unusual stroll through gentlemen's erotica demonstrates that pornography is timeless.

Spain's unique Mosque-Cathedral has been a place of worship for both Muslims and Christians throughout its history.

A king's pet, a pope's gift, an artist's inspiration, and a tragic shipwreck.

Three connected pink triangles memorialize persecuted gays and lesbians throughout history.