This retro, UFO-like structure is a remnant of the Soviet-era circus.

The floor of this spectacular Baroque sanctuary is covered in memento mori.

This church is named for one of the most dramatic tales in the early Christian church.

The bones of prehistoric animals and early signs of human habitation have been found inside Malta's "cave of darkness."

This Stone Age solar temple aligns with the sun on each equinox and solstice.

Burial grounds for more than 1,000 bodies deep under the modern town of Rabat.

This unique building in the main square stands out among the city's typically Baroque architecture.

Ancient mysterious ruts carved in the bedrock.

This replica medieval European village in the Dominican Republic was built by a Hollywood set designer.

Europe's oldest still-operational tea farm also boasts a spectacular view.

This abandoned five-star hotel is now a five-star urban exploration destination.

Legend has it the lovelorn tears of a princess and a shepherd boy formed the blue and green twin lakes in the Azores archipelago.

One of few vertical lava tubes in the world accessible by foot.

As the highest point in the Mid-Atlantic range this stratovolcano offers spectacular views.

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

"Holy Wisdom" overlooks the city that became its namesake.

Sofia's legislative center is continuously reinventing itself.

A Bulgarian monument to Russia's role in World War II is constantly being painted in pop culture protest.

Underneath this Byzantinian church lies a necropolis filled with ancient tombs and the ruins of previous churches.

A striking symbol of the Bulgarian capital.

A collection of art from Bulgaria's time as a communist state.

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

The smaller of the three towers of San Marino is a former prison inaccessible from the ground level.

High in the clouds of San Marino sits an ancient tower with some curious prisoner graffiti.