"The earliest pyramid was the step pyramid of Djoser (2668–2649 BCE) at Saqqara, and was an evolution of the traditional mastaba tomb, a bench-shaped superstructure" in Booth, Charlotte (2020). How to Survive in Ancient Egypt. Pen and Sword History. p.13. ISBN978-1-5267-5352-6.
"Tchogha Zanbil". UNESCO World Heritage Centre. Retrieved July 15, 2017. It is the largest ziggurat outside of Mesopotamia and the best preserved of this type of stepped pyramidal monument.