Dendara, July 16, 54 BCE, began the reconstruction of the temple dedicated to the goddess Hathor. Founded under Ptolemy XII, the temple studied here stands at the end of an architectural tradition developed over three millennia. Its state of conservation is exceptional. It is the latest preserved monumental cult building of the pharaonic civilisation. It is a particularly well-suited testimony for an attempt to comprehend the architectural conception of a culture with which no modern society has kept any direct connection. The starting point of this study is a precise survey which constitutes the scientific documentation. The establishment of these data went along with the observation of indications, dimensions, orientations and alterations which allows to identify constant characteristics belonging to the process of designing the structure of the temple. This study uses no technical methodology but rather presents a research of knowledge through observation, hypotheses and verification. There is no pretension to exhaustiveness. This study tries to find, from the territory to the details, breaches, or to give access, into the knowledge belonging to the way of designing. The plans and sections are accompanied by a research which begins with a presentation of the nature of the architectural study of the building belonging to a disappeared culture. Then follows the study of the Egyptian temple and of the technical details of the survey. A building belongs to a territory. The absence of any documentation, the disappearance of vestiges dug out since the end of the 19th century as well as the actual policy of land reclaiming on the site made a cartography of the whole area of the ancient city necessary as a salvage. This led to some thoughts about the urban shape around the temple and about the limits of the space between the divine and the civil world. The reconstruction of a temenos wall brought with it a large reorganisation and renovation of the city and caused an important tabula rasa of civil districts. A global description of the building precedes the chapter concerning the organisation of the space. The world being set up around the god, it progresses from the most holy place towards the civil environment. The system underlying the height of the different spaces can only be determined when taking the heart of the temple as point of origin. Particular attention was devoted to the means which the ancient builders had at their disposal in order to control the precision of their accomplishment. Although rules concerning the outer measurements of the naos and the inner volume of the cella could be determined, it is impossible to reduce the dimensioning of the Egyptian space to a system of constant proportions. The study of the use of the space confirms this statement as it reveals that the functional elements of doors and windows do not follow any ideal formal rules. They are the result of a topological conception where geometric accuracy sacralises different needs; sometimes trivial when one considers light as a physical agent necessary to the daily functioning of human beings in a structure belonging to the divine. The intelligence and the accuracy of these accomplishments clearly required a global and initial conception of the architectural object. The durability of the building was the ultimate reason for the designers' research of technical quality. No single part of the construction, from the foundations to the top of the cornices, escaped this ancient concern. This led to an evolution towards a monolithic character of the masonry and the integration of solutions to contain factors of degradation, such as the rain. This concern also includes a tradition of a seismic culture as well as an execution which optimises the performance of labour and the materials. In parallel to this evolution on can observe the emergence of an ancient analysis of the phenomenon of differential sinking and the development of details which allow a dynamic management of major sources of destruction. Computer modelling helped to check the pertinence of some of these ultimate systems of management of deformation. From the temple of Hathor at Dendara one can conclude that the competence of building has attained a high degree of complexity and of meaning as far as the production of an architectural form is concerned which had to obey to an ideal of perfection and inalterability. Beyond the secular world, the formal conceptualisation of the divine universe also became an intellectual challenge with various referential levels. The architectural composition went along with an active research of technical solutions in order to optimise the art of building.