The burial chamber of King Sneferu’s Meidum Pyramid. c 2600 BC.
This was the first time a corbelled ceiling was used inside a pyramid – designed to spread the immense weight of the stone above it and ensure that the immense bulk of the pyramid would not flatten the king.
The stone was left undressed and the burial chamber never used. Sneferu had his sights set on a new location and a new pyramid: Dahshur.