Small church on top of a huge rock column.

Underground monastery and fortress.

The largest lake in the Faroe Islands seems to be held hundreds of feet above sea level thanks to an optical illusion.

This remote island village was in danger of depopulating completely until a tunnel was built to connect it to the rest of the world .

This isolated structure beckons adventurers with sublime views of the Faroe Islands.

This isolated island is often capped by its own fluffy cloud.

Walk through Czech history in Prague's largest graveyard.

A secluded art gallery hidden within the cellars beneath Tallinn’s medieval monastery.

An empty relic of the Moscow Olympics crumbles away in Estonia's capital.

Countless grotesque faces stare out from this eerie Prague art wall.

A Jenga-style cylindrical tower of books that appears to go on forever.

A church of bones, decorated with 40,000 human skeletons.

Two stunning 17th-century libraries and a cabinet of curiosities.

The ruins of a fairytale castle with a tumultuous history stand high atop the mountains.

Once part of an ancient international harbor, it's now an all-you-can-eat shrimp buffet for flamingos and other water birds.

Breathtaking Byzantine paintings cover the inside of this 12th-century church.

This former Cyprus flight hub is now a crumbling, abandoned ghost complex.

The water here is so clear you can see the mysteriously sunken ship from the surface.

This picturesque medieval monastery guards a small trove of historic treasures.

Once a state-of-the-art tuberculosis treatment spa, these ruins are now ruled by paintball players.

Yugoslavia's biggest underground airport lies in ruins.

A chain of 16 wondrous lakes formed as a result of the gradual dissolution of soluble layers of bedrock.

An ethereal glowing blue ocean cave in Croatia.

A massive cross stands as the sole resident of this water-locked Crimean crag.