The burial place of an obscure North African saint was turned into a macabre body preservation factory for the 17th-century Neapolitan elite.

The Habsburgs' royal collections of art and wonders.

The topiary maze at the Habsburg hunting lodge.

The beautiful baroque library of the Hapsburg empire.

The Pope’s secret escape route.

A Nesting Doll of Churches.

The final resting place of the poets Shelley and Keats.

A master of trompe-l'oeil creates a stunning, tourist-fooling dome out of a flat ceiling.

The Grand Lodge of Ireland is one of the oldest in the world, full of fantastical, elaborately themed rooms.

The oldest public library in Ireland.

The enchanting archway is the only surviving portal into Dublin's lost medieval wall.

The gorgeous library at Trinity College is home to remarkable treasures of Irish identity.

A 18th century graveyard and its astonishing cortege of macabre iconography.

Invisible bridge parts the waters, invoking biblical images and preserving the ominous feel of an ancient moat.

Oldest Museum of the Netherlands is a true cabinet of curiosities.

A solemn reminder of the infamous World War II war crime that massacred almost all the men in a small Greek town.

A miniature desert appears out of nowhere on the lush isle of Lemnos, like something out of a Greek myth.

A small island with shimmering pink sands, home to loggerhead turtles and rare plants.

One of the largest single-span stone-arch bridges in the Balkans looks like something straight out of a fairytale.

What once sat in the world’s spotlight is today a largely disused ghost complex.

An abandoned Byzantine fortress and notorious prison.

The Cycladic architecture makes this Athens neighborhood feel like an island paradise hidden in the shadow of the Acropolis.

Where commuters walk through remnants of an ancient Greek necropolis.

This 15th-century island fortress later served as home to the executioners no one wanted to live near.