The last pharaoh of the fourth dynasty if Shepseskaf, the eldest son of Menkaure.  The strong, centralized governments that marked his predecessors reigns fell apart during the reign of Shepseskaf. A number of nomes (provinces) declared independence, and he had continuous trouble with priests and religious leaders.  The nobility rebelled, and while the conflict never reached the point of open rebellion, it took several years to restore order to the country and continue with his building projects.

He didn't rule very long -- Turin says only 4 years, based on the fact that the latest year of his reign is the year after the first cattle count. Even though he was only on the throne a short time, though, he managed to finish his father's mortuary temple (although hastily done) and build his own monument.

Shepseskaf did not built a pyramid, but instead built a large, sarcophagus shaped mastaba in Saqqara. The mastaba he built is different from any others in Egypt -- called the mastaba el-Faroun, it looks like a huge sarcophagus, sitting in the sand. The model is unique. The mastaba is enclosed in a retaining wall, and, surprisingly, the blocks used to build the mastaba are generally larger than those used in the pyramids. The egyptians were getting very good at handling large blocks of stone. The mastaba is cased in white limestone except for the first row, which is red granite. THe mastaba was restored by Prince Khamewere, in the xx dynasty.  

We don't know why he didn't build a pyramid, like his predecessors. The theories abound: There are a few possibly reasons for this -- he was not really associated with the royal family and thus broke with the tradition of building at Giza, the building projects of his father and grandfather had exhausted the wealth of the family, that unrest in the country prohibited him from demanding the service of the workers, as a protest against the priesthood who revered the pyramid as a sun-symbol, no appropriate site in giza for another pyramid..no one knows.  it is possible that this was a provisional monument and he intended later in his rule to build a pyramid.

He is the oldest son on Menkaure, but his mother, Bunefer, is not of the royal line, which may have explained some of his problems with retaining power. His daughter, Khamaat, married the high priest in Memphis, Ptah-Shepsis.

Turin shows his reign followed by an unknown king -- this may be the "missing king" mentioned by Manetho, Thamphthis -- for two years. In some cases. Traditionally, Shepseskaf was the last leader of the dynasty, and with him, the great monumental builders of the period did not repeat themselves in later dynasties. When Egypt regained her stride in later dynasties, most of the effort focused on keeping Egypt strong outside of her borders.  THe resources and the resolve to build pyramids was fading.

pharaohs

Sneferu
Khufu (Cheops)
Kauab
Djedefre
khafre (Chephren)
Bakare
Menkaure
Shepseskaf
Djedefptah

monuments

Mastaba Faroun
Valley Temple