In the past years, a growing number of studies have addressed relationship between light, architecture, and ritual at various moments of the Middle Ages. These scholarly efforts have analysed their material from technical, philosophical or phenomenological points of view, revealing new dimensions on Christian culture. Focusing on Late Antiquity, this paper addresses the beginning of this process, when light first came to be consciously used in Christian spaces in order to enhance their symbolism. The presentation discusses the various approaches currently used to research light, arguing for the necessity of an interdisciplinary approach.