Four-story slides send people whizzing through the math department at this Munich university.

This German version of Universal Studios holds a vault of treasures from the NeverEnding Story.

A monument to the man who almost killed Hitler.

A fantastical 13th-century fortification sandwiched by a modern hotel in central Brussels.

Dummies recreate radiological discoveries from history.

A huge old mansion full of thousands of toys, each there to be used and played with.

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

The "beautiful" equation predicting the movement of all electromagnetic particles is engraved in front of Newton's tomb.

A closed London rail station created to cart away the dead still bears the marks of attempts to make it less morbid.

Shiny Brutalist box commemorates a pioneer of electricity and houses a railway transformer.

A vintage video game wonderland in downtown Reykjavik.

This tiny museum's sizable collection is jammed into a former underground public toilet.

The largest whale museum in Europe allows visitors to walk among life-size giants.

The 19th-century pharmacy (now a used bookstore) was featured in James Joyce’s "Ulysses," and has changed very little to this day.

The enchanting archway is the only surviving portal into Dublin's lost medieval wall.

Crouch down, stretch tall, and be sure to flail your legs to pay homage to the Monty Python classic.

The secret wartime bunker built on the platforms of an abandoned Tube station.

The 2,000-year-old beam is tucked within the pedestrian entrance to the old London Bridge.

What looks like a normal building is really a hollow facade hiding a subway vent.

A simple plaque on the facade is the only reminder that the treaty ending the American Revolution was signed inside.

An off-the-beaten-path boutique stuffed with an eclectic collection of upcycled goods.

A 16th-century fountain marks the site of a lost medieval cemetery once filled with mass graves.

In this Parisian garden's grotesque former life as a zoo it fed exotic animals to the bourgeois and put humans on exhibit.

Part modern art project, part traditional chapel, this see-through church is only substantial from the right angle.