These four fountains are said to have healing properties, with a glass of the 'miracle' water being given to Louis XII of France.

The John Snow Memorial marks the epicenter of London's 1854 cholera epidemic.

This medieval sanctuary's tree-framed door looks like a portal to a mythical realm.

The Metropolitan Police refurbished the blue box (perhaps not coincidentally) the same year "Doctor Who" returned to TV screens.

Now famous as the "Harry Potter bridge," this impressive concrete viaduct has long been an icon in its own right.

A makeshift shrine to the late rock star is still kept up on the nondescript façade outside 1 Logan Place.

The signs of a long buried road can still be found hidden beneath a London sewer grate.

The fountain marks the area where hundreds of accused witches were burned at the stake.

Rebuilt remains of a temple to Roman god Mithras.

The perfectly preserved underground rooms where Churchill plotted the war against Germany.

The train platform where Jews were sent to concentration camps is now preserved as a Holocaust memorial.

A labyrinthine underworld of tunnels and caverns hides beneath the city.

The martyr's wax-enhanced skeletal remains lie preserved in a glass case in the Santa Maria della Vittoria in Rome.

Installed in an act of one-upsmanship, the annual sundial in this church is also a symbolic victory for the Gregorian calendar.

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

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

2300-year-old Roman road connecting the empire.

The only "Egyptian" pyramid in Europe and the legendary tomb of Remus.

Architectureal fantasy quarter of Rome.

An alchemist's "magic door" stands in the middle of a Roman park.

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

This statue was given to France by the United States to commemorate the centennial of the French Revolution.

19th century pendulum and a clock restored by a rogue group of guerilla artists.

A scandalous Art Nouveau collaboration that set Paris all atwitter at the turn of the century.