The largest pyramid built by Khufu was built by over 100,000 men and took over 20 years to complete (history). It also took 2.3 million stone blocks weighing about 2.5 tons each (story). The construction method is very controversial, but we know that they built the structure layer by layer and added the tunnels and chambers by filling the blocks around the hollow parts. Because of the way they were built, there is virtually no space inside the pyramids. The reason this is important is that, unlike modern buildings, it is impossible for the pyramids to collapse due to natural causes or interference from humanity. It would be very difficult to deliberately try to destroy the pyramids, but there are solutions