The second-largest giant sequoia in the world.

The rusting remains of the largest assembled WWII fleet on the West Coast.

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

These official units of measurement—including chains and perches—lie hidden beneath tourists' feet in a popular London hub.

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

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

A nearly 500-year-old sculpture depicts a man eating a sack of babies, and no one is sure why.

An ancient theatre in the "little Rome of the Alps."

This French colonial post office is arguably the grandest in all of Southeast Asia.

This historic spot was where America's involvement in the Vietnam War officially came to an end.

The world's longest outdoor covered escalator system transports commuters through Hong Kong's hilly terrain.

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

This 2,000-year-old Doric bridge is still open to pedestrian traffic to this day.

The only visible reminders of an elaborate engineering project that kept the tower from reaching the tipping point.

Depending on how it is measured, this lighthouse can claim to be the tallest in Europe and the tallest conventional lighthouse in the world.

This statue of the great Argentinian car driver is located near a famous curve of the Monaco Grand Prix.

This saucy statue once caused outrage among locals.

A memorial to honor those who were killed in a Bastille Day terror attack in Nice.

A sign marks where the two bodies of water meet.

This abandoned NASA launch site is now a memorial to a trio of astronauts who were killed there.

Now a pedestrian bridge, this was once part of a narrow-gauge railroad that ran along the east coast of Kauai.

This saltwater swimming pool, which is the last of its kind in the United States, is slowly crumbling within sight of multiple high-end beachside hotels.

On Waikīkī Beach, a monument to four extraordinary individuals of dual male and female spirits who brought the healing arts from Tahiti to Hawai'i.

A series of waterfalls and pools that flow through the 'Ohe'o Gulch and into the ocean.