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

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

Known as the "Valley of the Moon," this Jordanian wadi is one of the most amazing desertscapes on Earth.

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

On any given day this sprawling market houses literally tons of government-regulated gold, gems, and precious metals.

This indoor ski resort has a mountain contained inside a mall.

A preposterously luxurious hotel with gold-plated iPads, Rolls Royce chauffeurs, and a staff that trains by watching "Downton Abbey."

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

A 19th century pearling and fishing village abandoned before Qatar's economic boom.

The building is a gigantic piece of art inspired by the shape of a desert rose.

A staggering number of rock carvings in an abandoned quarry.

A powerful cyclone once made one of the world's largest sinkholes completely fill with water.

Where artisans use centuries-old techniques to build traditional Arabian ships.

This remote British Imperial telegraph relay outpost drove men insane.

This beautifully restored fortification kept the city safe for centuries.

Traditional architecture and ancient irrigation systems are on display in this gorgeous mountain village.

This spectacular mosque houses the second-largest chandelier in the world.

An imposing Omani fortress surrounded by date palm trees.

This bazaar is one of the oldest in the Arabian world.

A sinkhole and now a swimming hole, too, full of dazzling turquoise water.

Once a favorite playground for the world's most illustrious guests, Hotel Nacional's secret weapons and bunkers reveal a more menacing side to its golden history.

A focal point of the Cuban government, this city square features one of the most iconic images in the country.

This 16th-century monastery was founded to cloister the daughters of wealthy local families.

These ruined Incan mausoleum towers still bear carvings of sacred animals on their blocks.