340 bicycles, 65 feet high.

The ancient mosaics here are considered among the finest in the world, and serve as a stunning record of Greco-Roman daily life.

A poignant memorial to a young boy whose death spurred a dramatic increase in organ donations in Italy—dubbed the "Nicholas Effect."

A luxuriant botanical garden below sea level.

The last moments of the ill-fated Pompeiians, frozen forever in plaster.

A Norwegian-born sculptor created these soaring guardian angels at the entrance to Hoover Dam.

This stretch of beach along California's central coast is a busy highway for the largest seal in the northern hemisphere.

This central Nevada cave is the spiritual home of ancient and enigmatic pictographs.

Northern Ireland's Brobdingnagian stepping stones.

A sweet symbol marks the place where torturous executions were once carried out.

California's own medieval Italian castle, authentic down to the 300-year-old iron maiden in the dungeon.

This private residence was the template for one of the most beloved television homes of all time.

Once the fastest ship from San Francisco to Tahiti, the Galilee now lays in pieces in three different cities.

The last remaining relic of San Francisco's glittering 1915 Panama Pacific Exposition.

Concrete strongholds stand guard over the Golden Gate.

This 16-foot, intricately detailed model of the Gearing-class destroyer has been called the most detailed model ship ever built.

A burnt orange monolithic dome structure perched on a hillside near Interstate 280.

The bullet-banged DIY suit of armour belonging to Australia’s most famous outlaw.

A serpentine highway twists and turns over the treacherous Norwegian Sea.

This railroad magnate's 19th century tower is more than a little bit out of place in the Nevada desert.

The former home of the Nobel Prize-winning American writer is now home to dozens of six-toed cats.

Hundreds of lucky felines haunt the ruins where Caesar was murdered.

This foolish Victorian sea fort was converted to a deluxe hotel.

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