Discuss as:

Hidden Planet: Richard Engel journeys inside Egypt's secret tunnels

Rock Center
The Great Pyramids of Giza are some of the most iconic images in the world, but 19 miles south of modern-day Cairo lies the Saqqara plateau, Egypt's oldest pyramid complex. Follow NBC News Chief Foreign Correspondent Richard Engel to Egypt, where he journeys through a network of underground tunnels beneath the Step Pyramid of Djoser.

Editor's note: New editions of Richard Engel's 'Hidden Planet' premiere monthly on the Rock Center iPad app. Download the app here.