These magnificent city walls rise from the barren sun-baked Spanish plains like something straight out of a fairytale.

A network of ancient Egyptian tombs built into the cliff face along the Nile.

Part shoe store, part sociopolitical art gallery, part zoo.

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

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

These Egyptian statues have survived for 3,400 years and were an acoustic wonder of the ancient world.

One of the most well-preserved temples of ancient Egypt.

An endless sea of white conical domes.

Ozymandias’ time-keeping temple.

An ancient instrument used to measure the waters of the Nile so Egyptian farmers would know whether to expect famine or flood.

The history and future of cannabis.

This gorgeous reading room houses the oldest and largest art history library in the Netherlands.

An Amsterdam street lined with antique shops each one dedicated to a different obscure collection.

A curious collection dedicated to human and animal anatomy and pathology.

The world's only museum devoted to the wonders of fluorescence.

A real-life "hobbit" cave in Flores, Indonesia.

Two monstrous faces loom over a village in Czechia.

This quaint Italian town keeps losing ground as the sides of its plateau slowly erode.

This dazzlingly turquoise mountain lake was created in the wake of a natural disaster.

An enormous dragon scales the walls of this 17-story temple.

Behind this beachfront shop lies a spectacular, colorful sea cave with an equally colorful past.

A world-class observatory in the California desert.

An extraordinarily ornate museum in San Diego holds wondrous anthropological treasures.

A hidden network of subterranean passageways lies tangled beneath Indianapolis' bustling City Market.