The Greatest Construction Mystery

The pyramids represent humanity's most impressive engineering achievement of the ancient world — and we still do not fully understand how they were built.

• Workers were skilled laborers, not enslaved people, with medical care and good food
• The Great Pyramid's base is level to 2.1 centimeters across 230 meters
• Muon tomography revealed a hidden void in 2017, after 4,500 years
• Coordinating tens of thousands of workers may have been as hard as the engineering

That precision has fueled centuries of speculation, including unfounded claims about alien builders.