Da Vinci's equestrian statue, 500 years in the making.

High atop the Eiffel Tower is a small apartment built exclusively to entertain the science elite and make the rest of Paris jealous.

This iconic Parisian bookstore doubles as the "Tumbleweed Hotel" for traveling writers.

In all of the 29 years it was in operation, no prisoners ever escaped successfully... or so they claim.

The blinking light atop the iconic landmark has been sending secret messages for decades.

This "synagogue" is not what it seems to be.

This quirky UFO-shaped curiosity is often mistaken for the airport’s control tower.

There are lots of hands and feet stamped in the cement in front of Grauman’s Chinese Theater, but Mel left behind something extra.

The private clubhouse for the members of the Academy of Magical Arts.

Hollywood's most famous landmark, the "temporary" sign that has stood for decades longer than intended.

High on a hill overlooking Los Angeles lives a world famous, high power conical Tesla Coil.

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

Visit on a Sunday morning to see some killer tricks.

This massive collection of British military artifacts includes the heartbreaking personal letters of the men in the trenches of WWI.

The last four extravagant street signs of London's historic banking street.

An architectural oddity hides in plain sight on this iconic London bridge.

Underneath a chalk hill in France lies what Hitler hoped would be the underground launching base for a devastating new weapon.

A 16th-century fountain marks the site of a lost medieval cemetery once filled with mass graves.

This demon atop the Notre-Dame de Paris looks utterly bored.

Indents in the pavement are all that remain from a grisly death machine in Paris.

This beautiful 150-year-old synagogue survived Italy's fascist period and the Second World War.

A copy of the famous statue can be found in this Florence piazza, along with one of the most breathtaking views of the city below.

This picturesque Umbrian city has a subterranean side that has long remained hidden.

Water and windows define this defensive Italian well.