Rebuilt several decades ago, its striking murals prevent it from being reconsecrated as a church.

UNESCO-protected ancient burial ground.

The ceiling of Prohodna Cave in northern Bulgaria affords a peek at the sky via two deity-sized-eye-shaped holes.

An architectural marvel that spans the Arda River, and has stories of a haunted past.

This massive concrete sculpture is said to be the heaviest communist monument on Earth.

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

This once-grandiose behemoth of a monument from the socialist era now sits quiet and closed up.

An abandoned saucer-shaped monument in the Bulgarian mountains.

This 5,300-year-old tomb with mysterious carvings crowns an Irish mountain.

A nun spent 16 years painting the stunning Celtic mural that covers the interior of this WWI memorial.

These gigantic skeletons tower over visitors and provide insight into the creatures that once ruled over Ireland.

This permanent collection of preserved bodies taken from Irish bogs is one of the leading authorities on such morbid mummies.

This museum is dedicated to the most famous Irish writers in history.

These azure waters were thought to lead to the Mayan Underworld.

A lovers' beach, tucked below the surface of the island, provides a safe haven for romance.

An island filled with hundreds of hanging, decomposing, decapitated dolls.

This gnarled old tree supposedly sprouted from seeds kept in the pocket of a 16th-century Spanish sailor.

This doorless 20th-century elevator doesn't stop or slow down.

Dedicated to the unsung history of human waste.

A steampunk-styled three-floor factory churning out art, activism, and electronic beats.

A psychedelic labyrinth on the San Francisco bay.

A huge musical instrument played by the ocean.

World's largest collection of serial killer artwork and other macabre exhibits.

This arts and culture cultural center explores the diverse cultural heritage of the American West.