This Luxembourg cave is covered in cryptic looking marks left by mining activity.

In the heart of Luxembourg's "little Switzerland" weaves a breathtaking natural sandstone canyon with a mythological past.

Below the altar in Saint-Willibrord Basilica rests the mortal remains of Luxembourg's patron saint.

The cave of a 12th-century hermit is still visited and venerated today.

This cryptic monument honors a mysterious dead woman, despite her identity being lost centuries ago.

An oil drilling mistake created this fountain that has been spraying water for over 150 years.

A collection of birches from across Sweden.

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

Remnants of a 4th-century church with vivid medieval frescoes and ancient sarcophagi hide beneath this old basilica.

The mystic whose incorrupt corpse still attracts the faithful.

This ritzy Italian market is built around a statue of an unforgiven heretic who was burned for his belief in an endless universe.

This hidden alley near the location of Rome's first theater was the site of a curious miracle.

Brass cobblestones mark the places where individual Holocaust victims were taken from their homes.

Architectureal fantasy quarter of Rome.

A fairy tale castle in modern Rome.

At the crypt of St. Mary of Eulogies and the Dead you are left alone to ponder mortality among piles of skulls.

This Italian stadium makes liberal use of fascist statuary to evoke classical sporting arenas.

A modern sliver of architecture in Roma.

A treasure trove of Renaissance-era funerary art in a Roman church built on top of Nero's grave.

This hydrochronometer was invented by a Dominican monk and is a prime feature in this garden.

One of several skulls claiming to belong to the beheaded St. John the Baptist is on display at this Roman church.

This former Roman Catholic Church still contains the embalmed hearts and organs of 22 popes.

St. Francesca Romana, patron saint of drivers, resides in the church she founded.

The skull of the patron saint of lovers lies in the Basilica di Santa Maria in Cosmedin—maybe.