Measuring a height of 139 meters (455 ft.), the largest of the three pyramids of Giza is one of the oldest edifices in the world. Yet, even after 4,500 years, this architectural masterpiece still leaves some questions unanswered. Christian Grosse, Professor for Non-destructive Testing at Technical University of Munich (TUM) has performed fascinating measurements at the Pyramid of Cheops in coordination with Cairo University. In this interview, he presents his experiences.