A detailed pachyderm supports Rome's smallest Egyptian obelisk.

The only remaining arch of the oldest stone bridge in Rome stands in the middle of the Tiber.

This curious, round temple is the oldest still-standing marble building in Rome.

The yawning maw of this pagan visage is said to bite off the hands of liars.

In the early Roman Empire, people deemed traitors and criminals were tossed to their deaths from this rock.

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

This is the oldest Roman-made bridge in the city still existing in its original state.

Historic fortifications form the boundary of Vatican City, but it’s not entirely surrounded by walls.

Breathtaking and huge 430 year old maps of Italy.

Eighty million natural history specimens call this gargantuan museum home.

A mysterious shape catches the eye in this 16th-century painting.

The watery entrance for condemned prisoners heading to the Tower of London is still visible along the Thames.

Six ravens are kept captive (but well-fed) at the Tower of London to prevent the fall of the Crown.

France's most famous cemetery, with some of its most curious tombs.

The very center of Paris is surrounded by a bevy of strange good luck rituals.

The tradition of open-air secondhand and antiquarian bookselling in Paris dates back to the Renaissance.

This structure atop a craggy cliff in one of the most beautiful parks in Paris boasts an unbeatable view.

The Argonaute submarine was the French navy's pride and joy in the 1950's.

Natural history museum celebrating biodiversity with a parade of taxidermy animals.

This museum houses an imposing skeleton army comprised of creatures great and small.

An icy lake tucked among jaw-dropping alpine panoramas.

A giant bug impaled on a 75-foot-tall needle.

Incredible labyrinth of man made caves.

The last bastion of Roman presence north of the Alps looms over a German town.