Farther south of the White Pyramid is the imposing and enigmatic Bent Pyramid. Like the Red Pyramid, this was built in the reign of Sneferu, probably before that pyramid, and apparently planned as a normal pyramid with straight sides and with the usual valley temple, causeway, subsidiary pyramid and enclosure wall. It has a base measurement of 619ft/188.56m and a height of 319ft/97.26m. The excellently preserved casing, constructed of slabs of Tura limestone slightly inclined downwards, gives a good idea of the original external appearance of other pyramids. The reason for the change of angle half way up the pyramid, from 54° 31 in the lower part to 43° 21, is unknown. Two theories have been put forward: either some unforeseen event may
have made it necessary to complete the pyramid quickly, or as plaster filled cracks in the interior and traces of timber supports suggests there were fears for the stability of the pyramid during its construction and the upper part was given a less steep angle to reduce the weight of stone.
The Bent Pyramid was first entered by an English traveler, M. Melton, as early as the mid 17th C. ln 1860 Le Brun found a small chamber in the interior. This pyramid differs from the normal pattern in having an entrance on the west side as well as on the N. The north entrance (difficult to negotiate) runs down from a height of 36ft/11m to an underground chamber from which a passage leads to another chamber on a higher level. The west entrance descends from a height of 111ft/33.9m to a third chamber on the level of the pyramid's base, from which a shaft runs down to the two lower chambers. This shaft could be closed by monolithic slabs of limestone (portcullises). All three chambers have corbeled roofs formed of overlapping courses of stone which are well calculated to support the enormous superincumbent mass. Apart from some scanty remains of animal mummies in the passages, all the rooms were found empty. It may be that there are other chambers not yet discovered. The name of the builder of the pyramid is indicated only by two painted inscriptions dating from the time of construction and two stelae bearing cartouches.