The 4,600-year-old Bent Pyramid of Sneferu

The Bent Pyramid is an ancient Egyptian structure located at the royal necropolis of Dahshur, approximately 40 kilometres south of Cairo. Built under Pharaoh Sneferu, it represents a transition from step-sided pyramids to smooth-sided pyramids. The structure rises at a 54-degree inclination, but the top section above 47 metres is built at a shallower angle of 43 degrees, giving it a visibly bent appearance.

Several theories explain this change in angle. One suggests the structure showed signs of instability during construction due to the steepness of the original angle, forcing builders to adopt a shallower slope to avert collapse. This is supported by the fact that the adjacent Red Pyramid, built immediately after, was constructed at 43 degrees. Another theory suggests the change was a stability precaution in reaction to a catastrophic collapse of the Meidum Pyramid while it was still under construction. A different hypothesis suggests the angle was reduced because Sneferu's death was nearing, though this is contradicted by the angle of the Red Pyramid.

The pyramid served as an experimental stage for the pyramid program. It is unique among approximately 118 Egyptian pyramids because its original polished limestone outer casing remains largely intact. Because it was the steepest of the classical pyramids, stone robbery was too dangerous to be practical. Structural engineer Peter James attributes this preservation to larger clearances between the parts of the casing, which acted as expansion joints to prevent destruction by thermal expansion.

In July 2019, the Bent Pyramid was opened to tourism for the first time since 1965. Visitors can reach two chambers that are 4,600 years old through a 79-metre narrow tunnel built from the northern entrance. The public can also access the 18-metre-high side pyramid, which is assumed to have been built for Sneferu's wife, Hetepheres.

Sources: Wikipedia, OpenStreetMap, Wikidata, Wikimedia Commons