These giant yellow bowling pins seem to be defying gravity.

One of the most well-known city festivals in the world.

World's largest barrel containing an inn.

It has an American Dream Car exhibit, Europe's largest Formula One collection, and many, many mannequins.

In this German city center, the streets have no names.

This 18th-century folly is one of Europe's rare "garden mosques."

A unique look into the bowels of a century-old funicular.

This Nazi-built amphitheater was constructed on a sacred mountain site used by various German cults.

Sitting in the basement of a castle, the largest wine barrel in the world is bigger than most apartments.

This historic funicular system combines the old with the new while offering delightful views over the surrounding valley.

Lines on the pillar of Heidelberg's Karl-Theodor Bridge record the dramatic heights of past floods.

It's good luck to be mocked by this monkey.

A preserved college lock-up that recalls a clubhouse approach to discipline.

A larger-than-life monument to the inventor of the Bunsen burner.

The jaw of one of humankind's earliest ancestors on display at an overlooked geology museum.

A famed artist's inspiring work of peace and tolerance.

While you wait to cross the street at a traffic light in Mainz, you might notice that the light is staring back at you.

Southern Italy's spinning top village.

The sunlight passing through the opening of this huge cave system creates a magical effect.

One of the largest squares in Europe contains an entire artificial island.

The oldest botanical garden in the world that technically isn't the oldest.

The world's oldest surviving anatomical theater, where "the dead are pleased to help the living."

One of the world's oldest working clocks is curiously missing the Zodiac sign of Libra.

Featuring the last fully walkable parapet walkway in Europe.