This paper presents a preliminary approach to the problem of royal tomb orientation in ancient Egypt from the early dynastic mausoleums at the necropolis of Umm al Qab to the impressive subterranean chambers of the tombs at the Valley of the Kings (Biban al Muluk). This clearly shows that the correct orientation of the monuments, from the earlier mastabas to the later hypogea, was mandatory and that the sky plays a key role in understanding ancient Egyptian funerary monuments.