An Egyptologist thought a pyramid might have hidden rooms. It took almost 200 years and lidar to prove him right.

• An Egyptologist found a passageway in a pyramid almost 200 years ago. 
• The pyramid is badly damaged, and it was difficult to fully excavate.
• Recently, researchers used Lidar to map the pyramid's interior and found previously hidden rooms. 

In 1836, Egyptologist John Shae Perring was excavating the Pyramid of Sahure (also known as Sahura) when he noticed a debris-filled passageway.

An expert on floor plans for these types of structures, he surmised there might be storage rooms beyond.