This 4,000-foot-diameter hole is touted as "the most well known, best preserved meteorite crater on Earth."

Ancient pueblos built into the base of a natural canyon wall.

This historic national park is covered in the stunning ruins of red rock pueblos.

A monument to the one-armed geologist who led the first documented expeditions through the Grand Canyon.

This Native American settlement dates back to the Pueblo II period.

One of the most extensive and well-preserved collections of dinosaur footprints in North America.

Dramatic river bend surrounds a natural red-rocked pedestal.

Most-visited and most-photographed slot canyon in the American Southwest.

This bird-shaped rock formation defies gravity, time, and classification.

Some 2,000 carvings show this rare desert spring has been an oasis for travelers for over a thousand years.

Legends surround this jagged rock formation in the New Mexico desert.

A phenomenal assembly of pueblos in New Mexico is the most complete example of ancient ruins north of the border.

These wire animal sculptures commemorate the exotic inhabitants that once called the Tower of London home.

These mysterious Viking chess pieces spent centuries hidden on a remote Scottish island.

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

The ritual has been performed uninterrupted for nearly 700 years.

A statue of the legendary Celtic warrior queen who fought the Roman invaders stands in one of the cities she once destroyed.

Tucked away in the Tower of London is the weapon once used to execute high-profile prisoners.

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

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

Two plaques commemorate the site of Shakespeare's first theatre.

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

Scattered throughout London are ancient remnants of the city's former bounding wall.

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