During this period hieroglyphic writing became widely used, having been but rarely known before the age of Menes. A line of forts was built along the Isthmus of Suez to stay invaders from Asia. Tribes on the south were brought into subjection and pledged service to Egypt in time of war. Stone quarries and mines were developed and granite ranges sought and found. In the sixth dynasty one man-of-war sufficed to accompany the transports sent to bring granite for the kings' tombs from the southland--a fact recorded with pride by the pharaohs, since it gave proof of their far reaching might. From earliest times the Egyptian kings were builders, particularly of tombs, which during the Old Empire took the form of pyramids. Of far greater importance than the earthly abode was thought to be the tomb--the dwelling place for eternal years, consequently tombs and temples received the attention of Egypt's kings in early as well as later times. In 1897 the tomb of Menes was discovered. It was a brick-lined pit containing an inner chamber of wood. Around the mummy of the pharaoh had been placed the bodies of different members of his household. Similar to this were royal tombs until the Third dynasty, when stone was first used. To the kings of the Fourth dynasty belong the famous pyramids, unsurpassed by any subsequently built, and still today the wonder of the world. The Egyptians always located their cemeteries toward the west. Into the west the sun sank at night, and by the same way the soul started upon its long journey to the realm of Osiris, god of the future world. The irregularity of the Nile usually made it possible for the city of the living to grow up on its eastern bank, while across the stream, on the west shore, lay the City of the Dead. To the west of Memphis lay its cemetery or Necropolis, and while this remained the capital of Egypt, the pyramid-shaped tomb remained in favor. Sometimes the pyramid tombs were small; sometimes they were large. More than sixty have been found, and large numbers have doubtless disappeared for all time. Three, however, were made so prodigious in size as to cast into obscurity all the rest, and these have come to be called the "three Pyramids of Gizeh," quite as though they were sole examples of their kind. Khufu was builder of the largest; this is generally called "the Great Pyramid." His son Khafre built the one next in size, known as the "Second Pyramid," while the third, much smaller than these, was built by Menkure. Were we indifferent to the political development of Egypt, we would still wish to learn about these mammoth structures which are scaled each season by wondering tourists, and have excited the admiration and awe of travelers since the time of Herodotus.