A massive cave once a secret military base is now home to thousands of bats.

At this 16th-century monastery in rural Bulgaria, visitors can also spend the night.

A spectacular Bulgarian cave resembling a devil's head with a waterfall rushing down its throat.

Bizarrely shaped rock formations in northwest Bulgaria come with equally bizarre legends.

Down this Cracovian street resides a plaque with a stark message about the city's air pollution.

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

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

A statue honors the children who fought Nazis in Poland.

A tribute to the Polish insurgents who fought in the failed attempt to end their city's Nazi occupation.

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

This enormous 32-foot painting depicts Poland's greatest medieval battle in glorious detail.

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.

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

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

In the summer, the area around this sculpture transforms into a vibrant concert venue.

A striking symbol of the Bulgarian capital.

This building has two facades of clashing architectural designs.

A vast Communist-era exhibition space in the Bulgarian capital.

At first glance, this area seems like just another city park, but the lush landscape hides a dark past.

This historic black and white monastery is one of Bulgaria's architectural jewels.

This grubby wall is said to be one of the Earth's esoteric energy centers.

St. Mary's features one of the most spectacularly decorated cathedral interiors in all of Europe.

Extremely famous in his native country, this Cracovian painter is all but unknown beyond Polish borders.