This hunter-gatherer architecture is believed to be the oldest religious complex known.

These tombs were built into the side of a mountain so that ancient angels could reach the dead.

Roman ruins top white travertine terraces formed by ancient hot springs.

A marvel of Byzantine engineering under the streets of Istanbul.

In this historic region, homes and churches are carved into ancient volcanic rock formations.

Sacred Buddhist home of some spiritual monkeys.

This elegant neoclassical garden is a peaceful oasis in the middle of the Nepalese capital.

One of the largest Buddhist stupas in the world keeps an eye out in every direction.

This historic square in Nepal is home to temples dating back to the third century.

This Himalayan airport provides one of the most difficult landings in the world.

The largest and, arguably, most scenic fortress in Bhutan.

The small cliffside monastery known as the Tiger's Nest is said to be the meditation site of an eighth-century Buddhist master.

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

This mix of Islamic art, vintage vehicles, weaponry, architecture, and history is an ode to eclecticism. 

The enormous diamond-shaped building packs a trove of academic and literary treasures into one futuristic space.

A powerful tribute to the victims who suffered under Ethiopia's most devastating regime.

An otherworldly restaurant perched on the edge of a jagged cliff next to a medieval holy city.

The largest single-building tribal cultural center in the U.S. is an expansive museum in Oklahoma City.

Sitting in the arguable birthplace of the Wild West, this museum holds the largest collection of bronco busting bric-a-brac in the world.

Celebrate the history of the rich and truly misunderstood relationship between man and pigeon.

An old spiral fire escape dangles above a public courtyard in Midtown Oklahoma City.

An immersive art experience built by local arts collaborative, Factory Obscura, in the building formerly known as The Womb, a psychedelic arts center founded by the frontman of the Flaming Lips.

Travel through the hidden underbelly of the city in colorful tunnels filled with art and history exhibits.

Castle and secret tunnel withstood a siege until its owner was killed by the Holy Roman Empire, while sitting on the toilet.