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

This elaborately decorated, fairytale-like Romanian royal palace is one of the most striking castles in Europe.

A magnificent, glittering building tucked into a tiny Bulgarian mountain town.

The remarkably well-preserved final resting place of a powerful ancient Thracian king.

An ancient Thracian city where fire rituals were practiced on the largest cult altar in Southeast Europe.

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

In a long-dry lake bed, these groups of massive stone pillars bear a striking resemblance to clumps of everyone's favorite fungi.

Outstanding, eerie frescoes and decorations fill this 19th-century monastery.

A Romanian church built from one single oak.

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

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

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

This fairy-tale castle would make Dracula (who is said to have been imprisoned there) jealous.

Moss and stone turn this waterfall into an otherworldly liquid veil.

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

Some call this eerie forest of crooked trees the "Bermuda Triangle of Romania."

A spooky spot along the road where things mysteriously seem to move uphill by themselves.

A countryside Romanian cemetery filled with colorful crosses bearing lyrical, ironic, or satirical rhymes.

Hundreds of boat-shaped headstones fill this graveyard as part of a centuries-old custom with mysterious origins.

An industrial site turned into Hungary's most cherished natural wonder.

A beautiful display of nearly 50 bells crafted with a unique design and distinct sound.

The abandoned military base looks like a post-apocalyptic wasteland.

One of the largest barracks of the Austro-Hungarian monarchy's military is now an abandoned ruin.

World's tallest cigar-shaped radio tower.