Abandoned Nazi train station turned underground astroparticle laboratory.

A statue of a boy looks up at where the famous rival to the Leaning Tower of Pisa once stood.

The world's largest sundial can cast a shadow more than 1,600 feet long.

Climb inside an iron crystal magnified 165 billion times its normal size.

Red, white, and blue painted steps along with a Union Jack celebrate the outcome of Gibraltar's 1967 referendum.

This bell stars in a tragic love tale and is said to make wishes come true.

A statue honors the children who fought Nazis in Poland.

This hidden collection of everyday objects illustrates life within communist Poland.

A menacing statue of this mythical creature can be seen at the legendary site of the monster's lair.

The giant statue and its model solar system honor the native Pole who declared that the Earth revolves around the Sun.

The Polish capital has had a deep connection to its guardian mermaid for almost a millennium now.

Step back in time and witness the fall of Constantinople.

This remarkably well-preserved Egyptian plinth is pretty well traveled for a giant piece of stone.

This Austrian museum celebrates the work of famous forgers and their inimitable imitations.

A spherical "micro-nation" in the heart of Vienna.

Giant WWII fortresses that fired 8,000 rounds a minute, now home to thousands of pigeons.

Built to give thanks for the passing of a plague epidemic, this cathedral is a one-of-a-kind architectural hybrid.

Op-art architecture designed for happiness.

A silly medieval mural preserved on the side of a Viennese house.

This modernist church's massive sci-fi dome may be one of Latin America's largest.

Founded as a refugee camp, now a popular tourist spot.

At this faithfully preserved medina off the Moroccan tourist circuit you can walk through six centuries of history in one day.

Thousands of flowers create enchanting pink tunnels over the city streets.

Thousands of tourists and residents in Cologne affix "love padlocks" on the Hohenzollernbrücke Bridge to symbolize their affections.