The medieval center of the Islamic world was also once the seat of Saladin's sultanate.

A hyper-remote desert cave dramatized in "The English Patient."

This 7th-century monastery was sacked by Saladin.

Giant pigeon houses packed into city streets in Egypt.

It might not be the prettiest pyramid in Egypt, but it may be the muddiest.

The deadliest diving spot in the world is also a stunning geological marvel.

Brightly painted boulders scattered throughout the Sinai Desert.

A preserved oasis with traditional Andalusian-style architecture and beautiful views of the Nile.

This ancient structure is widely thought to be the oldest intact pyramid in the world.

A massive work of modern art that appears to be a crop circle in the middle of the desert.

An alien landscape of chalk-rock in the Egyptian desert.

An ancient city exhumed from the depths of the ocean.

A salt lake dotted with steaming limestone chimneys.

Rimmed by white crusts of salt on every edge, Lac Assal is one of the saltiest bodies of water in the world.

Mount Nyiragongo has erupted at least 34 times since 1882 and is home to the world's largest lava lake.

The most biologically diverse protected area in Africa is also the most dangerous.

One of the last refuges of the endangered eastern lowland gorilla.

Home to pygmy hunter-gatherers, hundreds of animal and bird species, and the strange okapi, or forest giraffe.

The world's only facility where orphaned mountain gorillas are cared for.

This moss-covered, rocky outcropping looks like a mythical beast resting in the water.

Legend says this remote, “bottomless” lake was created by a curse.

Camels and crocodiles share the black waters of this stunning Saharan oasis.

Amidst political unrest, this Roman Catholic Cathedral has helped organize peace talks.

Once a bustling fishing village and trading post, today these Cape Verde ruins provide a home only for seabirds and turtles.