The solemn exterior conceals an opulent interior of this 17th century church.

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

Baroque celebration of the end of the Great Plague of Vienna.

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.

A museum dedicated to a Cold War era sausage.

Cold war icon and onetime "hole" in the iron curtain.

The popularity of Sherlock Holmes led to the creation of his fictional address, turning the orderly London street numbers askew.

The signs of a long buried road can still be found hidden beneath a London sewer grate.

The topiary maze at the Habsburg hunting lodge.

Vienna's giant wonder wheel had a starring role in one of the greatest noir movies of all time.

Gaudí's famously flamboyant architectural style is on full display in this sprawling park and garden.

The final resting place of soldiers' loyal canine companions.

A book bound in the skin of an infamous criminal, along with countless other specimens.

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

360° views of the city plus five floors of optical illusions and hands-on science.

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

A 200-year-old collection of oddities and medical paraphernalia.

Displaced highlanders would take shelter from the wet Scottish climate under the large walled bridge at Glasgow Central Station.

This stately monument has been wearing a traffic cone hat for decades much to the delight of the locals.

The crypt of the imposing Stephensdom holds royal intestines and thousands of skeletons.

Terrifying derelict military hospital once housed a recuperating Hitler.

Incredible labyrinth of man made caves.