Pyramid of Senusret II

29.2275°N, 30.9714°E.

Twelfth-Dynasty pyramid at el-Lahun, on the eastern edge of the Faiyum, built for pharaoh Senusret II, who reigned approximately 1897–1878 BCE. Original base 107 metres per side; original height 48 metres at a 42° slope. Excavated by Flinders Petrie in 1889. The construction technique combines a limestone-block frame around a natural rocky knoll with mudbrick fill and an outer casing of fine Tura limestone. The substructure entrance was deliberately concealed on the south face rather than the north — the first royal pyramid in Egypt to abandon the standard north-facing entrance, possibly to deter robbers — but the burial chamber had still been emptied in antiquity. The pyramid town of Kahun, built immediately east of the complex to house the workforce and later the mortuary cult staff, is one of the best-preserved planned settlements known from the Middle Kingdom and produced the Kahun Papyri, including the earliest surviving veterinary, medical, and mathematical texts.

The pyramid moved its door and the architects who lived next to it left behind the best record of Egyptian arithmetic before the New Kingdom.