No one's quite sure where this quirky university tradition originated.

The only arched bridge made of stone on the entire Mississippi River.

The only museum with its curator—and her pets—buried inside.

Go inside to really appreciate this 500-year-old technological masterpiece.

Thousand-year-old Viking runes adorn an ancient Greek lion at the entrance to the Venetian Arsenal.

This Renaissance palace features a unique architectural design and is now home to the Ferrara National Art Gallery.

This cliff-face port is considered a masterpiece of mining engineering.

Estonia's largest creative city is a vibrant bohemian hub located within a former industrial complex.

Straight out of a nightmare, barcode-faced babies climb up and down Prague's television tower.

This endearingly discomfited urinating statue commemorates the sneaky pees had by us all.

This irregularly shaped sea fortress has defended not one but three different sovereign states.

This immaculate and historic water garden culminates in a massive stone dining table with an inset fountain for chilling the wine of the Cardinal's guests.

This quaint Italian town keeps losing ground as the sides of its plateau slowly erode.

A 16th-century horror show built in a lovely Italian garden.

A daily replay of the experiment that proved the rotation of the Earth.

The sounds of the world's largest fully functioning pipe organ dazzle shoppers at a Philadelphia Macy's.

This elaborate towering structure was once famed for its revolutionary height.

Yo, Adrian!

A monument to the three wars that led to German unification towers within a Berlin traffic circle.

These former Nazi anti-aircraft towers offer a singular view of the north of Berlin in the summer, and a sanctuary for bats in winter.

Where Venice's gondolas go for a tune-up.

Two stone columns flank the grand Venice square, but there were supposed to be three.

This spooky statue sits outside a famous Prague theater.

A series of playful yellow penguins share a serious message about the environment.