Daily usage of a work built environment quite always determines the efficiency and the living experience of the employees it hosts. This is the objective set by the present architectural proposal in the context of the open architectural competition for the new office facilities of the EYDAP. It aims at the optimal understanding of the given needs and the design of a contemporary workplace building. For the present proposal, the main source of inspiration was found in the historical route of the main mission of EYDAP, the water supply of Athens. Functionally and historically a landmark building of the Athenian water supply system was the reservoir of the Hadrian’s aqueduct in the region of Kolonaki. It is difficult to find a more suitable source of inspiration for the accommodation of EYDAP’s employees within a structure. The building of the ancient roman Adrian tank was translated with modern architectural values, into an office building that refers to the future. The volume of the new building is based on rectangular and cubic shapes inscribed within a long single volume. It has 4 above-ground floors and on one basement floor. In the further analysis of the building volume, big recesses and plateaus are placed on each floor of the building that will be used as open spaces for public relaxation and provide better lighting and ventilation to the offices. An essential gesture to improve these outdoor spaces, but also the building, is the design of 3 large atriums that provides more natural lighting and ventilation in all outdoor and indoor spaces. Inside the new building, all its uses and individual spaces were designed based on the requirements and the daily working operation of EYDAP. The interior design of the office space follows the international standards of workplaces that aims at the optimization of work production and living. With these specifications, we create a human-centered building, which puts at the spotlight, not only the work production but also the well-being of its human work force. The architecture of a building reflects the society which serves. The aesthetic approach of a “landmark” building, like the one in this architectural proposal, aims at the simultaneous promotion of the values that we would all like to characterize our society and the values that characterize the social contribution of EYDAP.