Professor Michel Barsoum and colleagues have found scientific evidence that parts of the Great Pyramids of Giza were built using an early form of concrete, debunking an age old myth that they were built using only cut limestone blocks.
Scanning electron microscopy micrographs and elemental maps of bulk of Lauer sample showing (a) secondary and (b) backscattered images; the rest of the images represent elemental maps of Ca, Na, Si, and S. Note that the size of the calcite aggregates is 50–500 mm.