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

At the base of the Golden Gate Bridge, a small sign basically begs for a high-five.

Beneath the southern end of the Golden Gate Bridge is the “Gibraltar of the West Coast,” a fort built to protect the San Francisco Bay from naval attack.

The marker offers a rare chance to be in four U.S. states at once, though there's some controversy over its geographic accuracy.

The second-largest giant sequoia in the world.

Quite simply the largest tree in the world (by volume).

A portrayal of two lamps embraced and in love.

This building has a giant piercing through one of its corners.

This fountain is dedicated to the workers who perished constructing the Fréjus Rail Tunnel.

This Torino museum honors a soldier who kept the city safe using barrels of exploding gunpowder, losing his life in the process.

One of the oldest and most significant collections of Ancient Egyptian archeology outside of Egypt.

When this funny little building went up in the 19th century, most people thought it would simply fall over.

Now an entertainment complex, the Lingotto building was once an avant-garde auto factory with a test track on the roof.

A fake medieval village in the middle of Turin.

The astonishing collection of an infamous criminologist.

Legend has it this gnarled old tree was planted by Tsar Peter the Great during his visit to London.

The handiwork of a underdog clockmaker who solved an impossible problem for an Empire, and forever revolutionized seafaring.

Thanks to modern navigational tools we now know that the true prime meridian runs through a park next door.

19th-century scientists would make the pilgrimage here to verify the precision of their measuring sticks.

A tribute to the intrepid explorer and his crew who perished in terrible conditions on an ill-fated expedition to the Arctic.

The world's largest collection of ship figureheads includes figures from legends and history alike, from Sir Lancelot to Abraham Lincoln.

A 1,215-foot tunnel transports pedestrians beneath the River Thames.