The pharaoh buried here, Niuserre Ini , was a Pharaoh of Egypt of the V. dynasty. Niuserre Ini was the younger son of pharaoh Neferirkare Kakai by Queen Khentkaus II, and the brother of the short-lived king Neferefre.
The core of the pyramid was built in steps which were then encased in fine limestone.
Its entrance is traditionally located along the north face of the pyramid shown on the picture. From the entrance, a passage first enters horizontally through the thickness of the encasing and then descends down into the ground below the pyramid. Three portcullisses blocked the passage. The slope of the passage decreased beyond the portcullis blocks and the passage slighly deviates to the east from there on, until it reaches the antechamber.
A door in the west wall of the antechamber leads to the king's burial chamber. The passage between the two chambers is located directly underneath the centre of the pyramid.
Both the antechamber and the burial chamber were lined with fine limestone and roofed with three layers of enormous limestone beams.
The pyramid of Niuserre has been excavated by Ludwig Borchardt. The description of the excavations (in German) has been given in the book
An English translation of an earlier description of excavations during 1901-1902 can be found as
Most of the best places to build a pyramid have been already in use by the predecessors of Niuserre. So, it was hard to find a good place. The place which has been used is located between the pyramids of Sahure (in its north) and of Neferirkare (in south-west).
The map on the right side has been made by Borchardt (taken from his report about the excavations of the Sahure pyramid).
At the northern (right) part one can see the remains of several buildings. These are the mastabas of some of the high dignitaries of the Empire. The left one is the mastaba of an Weser-kef-onch, while on the right picture we see the mastaba of Djedj-em-onch, between them the mastaba of someone unknown to Borchardt.
Instead, the left (southern) part contains the main part of the temple, and even a layman can see the completely different character of this part, starting from the different size and the completely different material used there.
If one considers the south part of the temple as a separate entity, it is at least symmetric. But the way leading from this temple down to the valley temple is even skew, and leads, essentially, to the natural path between the valley temple and the pyramid of the pyramid of Neferirkare. So, it seems reasonable that the valley temple was the valley temple of Neferirkare, and has been simply usurpated by (or shared with) Niuserre.