This unattributed sculpture in Amsterdam is hiding in plain sight.

This remarkably well-preserved Egyptian plinth is pretty well traveled for a giant piece of stone.

A marvel of Byzantine engineering under the streets of Istanbul.

Five sultans and their families rest in eternal splendor, teeming with overlooked beauty and drama.

A familiar otherworldly creature guards this 12th-century Scottish abbey.

This Scottish museum is the only one in the world to focus not on one religion but all of them.

Possibly the oldest living thing in Europe, more likely a pagan survivor.

There are plenty of wonderful panoramic vistas in Edinburgh, but not many are hidden smack in the middle of the Old Town.

Ruined castle with subterranean vaulted Goblin Ha' or "Goblin Hall."

A mysterious monument where a woman who records say never existed was burnt alive for being a witch.

A small island abbey is the final resting place of many medieval Scottish monarchs, including the real Macbeth.

A site of pagan worship which still attracts people looking for fairies.

The true age of this ancient stone circle is unknown, but its stunning vista isn't in question.

The ruins of this gorgeous clifftop castle look like something from a fantasy novel.

This series of Scottish caves has no clear purpose other than baffling historians.

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

The world's spiciest ice cream comes from Glasgow.

Beneath the city of Lourdes, France is a massive, concrete church.

The historic Masonic Lodge in which the first-ever female Mason was initiated.

The remaining relics of the patroness of Paris lie in a chapel under a striking double spiral staircase.

The spiral staircase hidden inside this giant Parisian column was likely built for Catherine de Medici's astrologer.

Twelve grave-faced marble angels guard the emperor's tomb at Les Invalides.

One of the oldest masonic museums in Paris.

Saintly bones pressed into a wax effigy of a Catholic superstar.