A natural arch offers panoramic views of Yangshuo's karst hills.

The meaning behind this triumphal Roman arch was a mystery until the early 20th century.

The world's largest natural arch was forgotten for over 50 years after its discovery.

A roadway designed for a visiting monarch.

A natural arch carved by a river gave its name to the so-called "Cave of Forgotten Dreams."

This unique structure is the only one of its kind in Virginia.

Ancestral Puebloan ruins, natural arches, and box canyons abound in this seldom-visited corner of Monument Valley Navajo Tribal Park.

Atop this arch, during the 16th-century, a sermon was given to those suffering from plague.

The second-largest natural arch in the Chartreuse Mountains.

Many people don't realize there’s a lot going on in—and below—the world’s tallest triumphal arch.

The "Black Arch" guards the entrance to the picturesque Glens of Antrim.

A strenuous, unofficial trail leads to spectacular views in one of America's most remote national monuments.

Unscathed for almost 2,000 years, the best preserved Roman triumphal arch is in a small southern Italian city.

A graceful natural rock formation stands astride the point where the Gulf of California meets the Pacific Ocean.

Tucked between a side street and a theater, this arch once led to a prestigious riding school, and now opens to a courtyard and community garden.

This one-of-a-kind Roman arch is not actually dedicated to the god Janus.

This striking arch, one of the first architectural elements constructed in Prospect Park, was recently restored to its original glory.

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

This magnificent arch is all that remains of a former smelt mill.

This clifftop arch is a natural stunner.

A triumphal steel arch on the side of a German mountain.

It's safe—and permitted—to walk across these twin natural sandstone arches.

When new viceroys were elected, they passed through this arch to cement the title.

A peace symbol in Northern Ireland is among the world's largest hedge mazes.