This research aims to accentuate the sustainability of the atrium, as an architectural suggestion and a tool with environmental value. As it has a recognizable structure with form and well-known function applied in the history of architecture, it is also related to beneficial results in the heating and cooling of the building of which it is part. It should be accentuated that, especially in Mediterranean climates, the atrium is encountered with particular types and connections to the wholeness of the structure. In the urban web there are buildings with courtyard, backyard, interior atrium, garden, or semi-outdoor spaces. The pre-mentioned instances contribute with vital importance to the heating and cooling of the building, as well as to the ventilation and the reception of natural light. Thus, the atrium presents a substantial solution to the amelioration of the microclimate of a building and even of a neighbourhood, via the exploitation of the characteristics of the construction (materials, openings, height, function) in combination with the exterior conditions. The traditional form of courtyards could lead to adaptation and mitigation measures, regarding the impacts of climate change. Moreover, the case of Athens, as an instance of a Mediterranean city, presents an interesting result of rules and regulations for the organization of the population’s growth, which created blocks with courts in their centre, structuring the analysis of built-and-empty spaces. The microclimate and the conditions of improving the land uses of the buildings with such courtyards is of great importance, especially in city-centres with the phenomenon of urban-heat-island, like Athens. Therefore, the atrium and its tradition seem to be a vital solution of sustainability for the adaptation to the climate change and the maintenance of life quality.