This lucky bronze frog was gifted to Madrid by a casino.

A lush indoor jungle fills this bustling Madrid transportation hub.

An ancient Egyptian temple in the middle of Madrid, Spain.

Over two centuries old and counting, Madrid's massive botanical garden contains one of Europe's only desert environments.

For decades, Puerta del Sol has been illuminated by a giant, guitar-wielding bottle of sherry.

The remains of the second-oldest zoo in Europe can be seen within these library gardens.

This sweet-toothed bear searching for snacks has been a symbol of Madrid for decades.

Madrid's romantically ornate crystal palace has been offering shelter to plants and art for over a century.

Also known as the Blue Church, the building was consecrated to the daughter of Andrew II.

Stockholm's narrowest alley is barely over two feet wide.

Walking through this narrow gorge will make you feel like you've fallen into a fairytale landscape.

A replica of the home of a famous fictional troll family.

The only surviving piece of Copenhagen's 16th-century defensive wall.

The site of the first battle of World War II.

When this 18th-century observatory's meridian was moved, it set Sweden's time back by 0.04 seconds.

This former KGB building is now a museum memorializing the people who suffered during the Soviet regime.

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

An artificial date palm stands as a memorial to Warsaw's Jewish community.

Special benches that play Chopin's music are scattered throughout his native city.

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

This extensive collection covers thousands of years of Polish military history.

Finland's oldest astronomical observatory once played a crucial role in seafaring and timekeeping.

These 18th-century paintings of Warsaw were used to reconstruct the city after World War II.

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