"The Donut" was built as part of an expensive, ill-fated engineering endeavor.

All that remains of the fishing-vessel-turned-warship is its weathered hull.

The hidden "ballroom" under a mansion lake was built by a criminal who ate a cyanide pill during his trial.

No building in the world leans as far as the so-called “Leaning Tower of Abu Dhabi.”

Planned as the world’s first zero-carbon city, it had lofty ideals—but is only 5 percent completed and aiming for 50 percent carbon-neutral.

This fortress sits atop a centuries-old well system.

The rocks around this mountain are filled with so many carvings that the area became known as the "open library."

These desert alfalfa farms redefine the meaning of crop circles.

For centuries, Jeddah’s old town was a major trading port and a point of entry for Hajj pilgrims traveling by sea.

Climbing the "mountain of frustration" is no easy feat.

A network of tunnels runs underneath the buildings of this ancient village.

Village of slate houses, built on a white marble outcrop.

Lions carved into the rockface adorn these two tombs built into the mountains of Dadan.

This mesmerizing, colorful structure looks like a tent made from stained glass.

In the middle of a barren desert, a massive, solitary rocky thumb juts out.

Within the Saudi Arabian desert lies a 2,000-year-old ghost town made of stone and mud.

More than 100 monumental tombs carved into rock are preserved at this ancient Nabataean site in the Arabian Desert.

An unfinished tomb carved into a giant boulder in the Arabian Desert.

These towering cliffs jut dramatically from the middle of a barren desert.

A more chill but no less fascinating version of the famous ancient archeological site.

An ancient capital city that dates back 3,000 years old and harbors many surprises.

This ancient town is full of stunning Ottoman architecture and streets so narrow trash collection is done by donkey.

Gladiators battle and chariots race daily in the ruins of a once-great Roman city.

A 19th-century fortress and collection of artifacts offer a tour of Saudi history.