Pyramid:

  Base: 105m

  Height: ±75m

  Slope: 57°15'50"

The last pyramid to be built at Dashur is dated to the reign of Amenemhat III, towards the end of the 12th Dynasty. It was located in the South of Dashur, quite near to the edge of the cultivated land. The choice of location was probably inspired by the presence of a nearby lake.

The core of this pyramid was made up entirely of mudbricks. This core was encased in limestone blocks that were joined together by dovetail shaped cramps. Most of the encasing blocks were removed over the centuries by stone robbers, so that only a mound of mudbrick blocks remains.

The pyramid had a base length of 105 metres and a slope that with its 57°15'50" was slightly more steep than the pyramid of Sesostris III, which stands a bit more to the North. It rose to an estimated height of more than 75 metres.

Unfortunately, the pyramid was built too close to the valley and to Lake Dashur and the mudbrick core was weakened by ground water. The substructure was too complex to support the weight of the pyramid. Wooden beams were intended to give the roofs of chambers additional support, but ultimately, work on this pyramid was largely abandonned.
 

3-D reconstruction of Amenemhat's pyramid at Dashur, showing its complex internal structure.
Source: Lehner, Complete Pyramids, p. 179.

The pyramid's substructure is one of the most complex in the history of Ancient Egypt. Like Snofru's Bent Pyramid, which stood at some distance to the West, this pyramid has two entrances. One entrance was in the south side of the East face of the pyramid, the other opposite that in the West face. Both entrances start with a descending passage, at the end of which there are some chambers. But before getting to the first chambers, each passage has a corridor splitting off to the South, leading to two South Tombs. This is reminscent of the South Tomb in the complexes of Netjerikhet and Sekhemkhet at Saqqara, and the satellite pyramids of the Old Kingdom complexes.

Following the western entrance corridor into the first chamber leads to a set of chambers to the North where the sarcophagus of a queen named Aat was found, along with the remains of her canopic chest.

Continuing along the western entrance corridor, there is a second set of chambers to the North, with a burial chamber for a second queen. Both in Aat's and in the second queen's burial chamber, some bones were found of women aged around 35 and 25 respectively.

A corridor connects the two queen's chambers with an antechamber. The chamber to the south of this antichamber leads to the eastern entrance corridor, while a corridor in the East wall of the antechamber leads to another set of chambers and to the King's unused burial chamber. The sarcophagus inside this burial chamber was made in granite. It was decorated to resemble the Enclosure Wall of the complex of Netjerikhet in Saqqara, including a larger bastion in the Southeast where the "entrance" was located.

Eventhough the pyramid itself was abandonned due to structural problems, a temple, causeway and Valley Temple were constructed. Only little remains of the mortuary temple. The Valley Temple consisted of two open courts, located on a different level. The front of the first court was heavier and formed a pylon-like entrance.

Archaeological research has shown that this pyramid was abandonned somewhere around Amenemhat's 20th year, after the burial of Queen Aat. The corridors were stuffed with mudbricks, perhaps in an attempt to add further support to the pyramid or to mislead any tomb robbers. The king would ultimately be buried in a pyramid at Hawara, near the Fayum Oasis, to the South of Dashur.