Hungarian self-built castle.

A museum in the childhood house of a medical pioneer.

Built in 1870 at the bridge that connected Buda and Pest, this spectacular incline railway was almost lost forever during World War II.

This Hungarian castle was built out of cardboard and wood until it proved so popular that it got upgraded to stone.

Known as the Hintz House, this medieval pharmacy has been an apothecary's haven for nearly 450 years.

The European towns of Brașov and Râșnov each have proud signs reminiscent of the Hollywood sign.

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

This massive underground salt mine now holds a sci-fi theme park in its depths.

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

A spectacular Bulgarian cave resembling a devil's head with a waterfall rushing down its throat.

A flamboyant five-story building in Bulgaria resembles a crawling snail.

This tiny Bulgarian town offers a stunning location in the mountains and a storied history.

This small 16th-century church in Athens is almost entirely surrounded by a modern building.