The Pyramid of Raneferef, also known as the Pyramid of Neferefre, is an unfinished Egyptian pyramid from the 5th Dynasty, located in the necropolis of Abusir, Egypt. After the early death of Pharaoh Raneferef, the unfinished building was reconstructed into a geometric mastaba, becoming the burial place of the deceased king. Despite the demolition of the actual pyramid, the complex was augmented through extensive construction of temples by Raneferef's successors.
The Pyramid of Raneferef was started with a base length of 65 metres (213 ft) and thus could have been the second-smallest king pyramid in the Old Kingdom of Egypt after the Pyramid of Unas. The planned height and side tilt are unknown, as the casing stones were never attached. The pyramid should have received a stepped core, covered by fine Tura limestones, but construction did not continue above the first step.
The pyramid was not directly built on bedrock, but rather on a foundation made of large limestone blocks. These were cut from the local bedrock while excavating a pit at the pyramid's center. This pit was to receive the essential substructures (most notably the burial chamber), a construction technique common to all 5th dynasty pyramids.
The core layer of the pyramid comprises an exterior wall made of huge roughly-hewn limestone blocks, some up to 5 metres (16 ft) long, 1 metre (3.3 ft) wide and 1 metre (3.3 ft) deep, which formed the extent of the step in two rows. The pit for the burial chamber and the entrance were covered with a similar wall built from smaller blocks. This strategy allowed workers to work simultaneously on the foundation and on the first step of the pyramid. The height of the blocks, which were laid in horizontal layers, was about 1 metre (3.3 ft). Interspaces were filled with clay mortar. Apparently, the placement of the blocks was more careful in the corners than on the edges. The interior of the steps was filled with gravel, sand and mud. This offered a considerable saving of labor compared to the large and more accurately hewn limestone cores of 4th Dynasty pyramids, but also that the core is very sensitive to erosion. In fact, this construction technique is responsible for the ruinous state of all 5th and 6th Dynasty pyramids.
The death of the pharaoh led to a stop in the construction works and design alterations were made to use the building for the funeral. The first step, about 7 metres (23 ft) high, received a cladding from rough limestones with a side slope of 78°, similar to a mastaba. This was covered with a layer of clay, in which flints were incised. The term "hill" (iat), found in the Abusir Papyri, might be connected with the primary hill myth.