The massive cave church of Cairo's Zabbaleen community is one of the largest Christian churches in the Middle East.

An endless sea of white conical domes.

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

Egyptian treasure trove of fossils documenting the whale's transition from land mammal to sea creature.

An ancient city exhumed from the depths of the ocean.

Stenciled handprints and wall paintings dating back 10,000 years, some of the earliest forms of cave art.

The inspiration for the Patagonia Clothing logo, Cerro Fitz Roy turns pink at sunrise.

Mother Nature outdoes herself with this stunningly beautiful set of caves carved into marble.

Pilgrims each carried a brick to the top of Mount Monserrate to help build this historic sanctuary in Colombia.

The first declared National Monument in the United States.

Just a man taking his prehistoric pet for a stroll.

A massive underwater sinkhole made famous by Jacques Cousteau.

Enchanting cave with a river crashing through the roof.

The caldera of this mini-volcano has been turned into a naturally heated mud bath.

This everlasting lightning storm may be the world's largest generator of ozone.

This Costa Rican topiary park is a surreal garden of unearthly delights.

One Costa Rican island is so beset by illegal shark poachers that the local rangers have built an entire bridge with their confiscated gear .

Where dogs like the rare "Fire-Tailed Border Cocker" run free on the mountainside.

These mysterious ancient stone spheres were created by a civilization lost to time and are now mostly lawn ornaments.

This neon blue river gets its color from a unique mix of bacteria and volcano minerals.

Sloth rehabilitation center in the jungle of Costa Rica.

The Cuban revolutionary looks over the country from its highest peak.

Neo-cave art on the macro scale.

Roam the cradle of the Cuban Revolution with life-sized dinosaurs.