Rome's semi-secret peephole vista is also a former Crusader stronghold.

The 10,000 Torii shrine.

An ancient Scottish rock formation said to be the gravesite of a giant remains ensconced in legend and intrigue.

Amazing and mysterious Neolithic settlement on Scotland's Orkney Islands.

This hidden Art Nouveau courtyard is an opulent feast for the eyes.

This medieval castle overlooking the Elzbach river looks just like it did hundreds of years ago.

A meditative space out of a fantasy story.

The mysterious wonder of an underground waterfall is illuminated by multicolored lights.

This fantastical waterfall is hidden in a cave located in a cracked cliff.

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

The hidden lair of an alchemist rediscovered in a 2002 flood.

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

An Australian lake whose pink hue defies scientific explanation.

One of Antoni Gaudí's most classic buildings is well-known for its "dragon-back" design.

Construction of Barcelona's iconic (but controversial) church is expected to be completed in 2026—a century after the death of its architect.

Rising from the sea like a stone monster.

Eighty million natural history specimens call this gargantuan museum home.

These eerie outliers of the lightning bug family glow a mysterious blue color.

The atmospheric road was never meant to be so creepy.

Tiki luxury on Nob Hill.

A stunning, two-tiered waterfall made famous by poets, artists and the legend of a ghost dog.

The largest hot spring in the United States is, as the name suggests, a stunning show of natural color.

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

This frequently-photographed waterfall takes only a short hike to visit.