With the Hid Dynasty we have reached the age of the pyramid-builders. The most typical pyramids are those of the three great kings of the IVth Dynasty, Khufu, Khafra, and Menkaura, at Giza near Cairo. But, as we have seen, the last king of the Hid Dynasty, Snefru, also had one pyramid, if not two; and the most ancient of these buildings known to us, the Step-Pyramid of Sakkâra, was erected by Tjeser at the beginning of that dynasty. The evolution of the royal tombs from the time of the 1st Dynasty to that of the IVth is very interesting to trace. At the period of transition from the predynastic to the dynastic age we have the great mastaba of Aha at Nakâda, and the simplest chamber-tombs at Abydos. All these were of brick; no stone was used in their construction. Then we find the chamber-tomb of Den Semti at Abydos with a granite floor, the walls being still of brick. Above each of the Abydos tombs was probably a low mound, and in front a small chapel, from which a flight of steps descended into the simple chamber. On one of the little plaques already mentioned, which were found in these tombs, we have an archaic inscription, entirely written in ideographs, which seems to read, “The Big-Heads (i. e. the chiefs) come to the tomb.” The ideograph for “tomb” seems to be a rude picture of the funerary chapel, but from it we can derive little information as to its construction. Towards the end of the Ist Dynasty, and during the lid, the royal tombs became much more complicated, being surrounded with numerous chambers for the dead slaves, etc. Khâsekhemui’s tomb has thirty-three such chambers, and there is one large chamber of stone. We know of no other instance of the use of stone work for building at this period except in the royal tombs. No doubt the mason’s art was still so difficult that it was reserved for royal use only. Under the Hid Dynasty we find the last brick mastabas built for royalty, at Bêt Khallâf, and the first pyramids, in the Memphite necropolis. In the mastaba of Tjeser at Bêt Khallâf stone was used for the great portcullises which were intended to bar the way to possible plunderers through the passages of the tomb. The Step-Pyramid at Sakkâra is, so to speak, a series of mastabas of stone, imposed one above the other; it never had the continuous casing of stone which is the mark of a true pyramid. The pyramid of Snefru at Mêdûm is more developed. It also originated in a mastaba, enlarged, and with another mastaba-like erection on the top of it; but it was given a continuous sloping casing of fine limestone from bottom to top, and so is a true pyramid. A discussion of recent theories as to the building of the later pyramids of the IVth Dynasty will be found in the next chapter.