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

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

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

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

An abandoned saucer-shaped monument in the Bulgarian mountains.

This 11th-century structure is one of the oldest churches in Romania.

This museum offers a journey back to the Belle Epoque era of Romania.

A memorial museum to the political prisoners who were held at Sighet Prison, once one of the most feared places in Romania.

Climbing to the top of the cathedral's bell tower offers sweeping views of these medieval ruins.

A Romanian church built from one single oak.

Nine centuries-old fortresses guard the walls of this medieval Romanian city.

A collection of items from a way of life that no longer exists.

Romania's only crater lake with water as pure as if distilled.

Even drowned in an ocean of toxic waste, the remnants of this Romanian village stand tall.

The Natural History Museum that time forgot.

This snug medieval lane is one of the narrowest streets in the world.

One of the oldest churches in Romania is believed to have been built on the site of a pagan temple.

Romania's "Red Ravine" is a little-known natural wonder that bears a resemblance to the Grand Canyon.

No one knows who built this strange cave of worship or exactly why.

A giant portrait of an ancient king looms over the river.

Once an opulent Art Nouveau hotspot, the Constanța Casino is one of Romania's most beautiful abandoned buildings.

The romantic botanic tunnel feels like a well-kept secret.

The legendary cliffside castle of three-time Voivode of Wallachia, Vlad the Impaler.

This solitary monastery may hold the remains of Vlad the Impaler (but probably not).