= Paper =
The aim of this study is to show the links between the Celtic god Lugus and landscape organization. We underline the important part of the light from sunrise – which has well known connexions with Lugus – in the process used by the Celts for their spatial orientation. By revealing the setting of a landmark, orientation constitutes a preliminary and essential step before the establishment of a space which will be intended to be inhabited by people. The analysis of Gaulish archaeological facts and Irish medieval tales perfectly highlights the relation of Mercury and Lug to strategic places which were used for the development of a human community: places of assembly, places where cities or provinces were founded, places on hilltop or located on a border, shrines, roads; moreover, some of them are frequently found in a same place, which demonstrates a real cohesion in the process of organizing landscape.