This paper seeks to investigate a new definition for architecture by unifying the three Vitruvian principles of firmitas, utilities, and venustas via a phenomenological approach in the interpretation and analysis of their role in defining architecture. The paper is composed in two main sections. The first section investigates the nature of architecture based on the mentioned principles, where architecture is interpreted and analyzed in terms of its “thingly,” “equipmental,” and “artistic” characters. While it seems that architecture could be in view of its “thingness” alone, or “equip mentality”, or “artless”, but each perspective reveals only a dimension of the nature of architecture. Therefore, the second section of this paper focuses on unifying the Vitruvian Triad, attempting to define architecture from the single stance of “architecturality” the sphere from which architecture is seen as a way of disclosing the truth in the desired life of humans in an architectural work. In this definition, there is the simultaneous presence of thingness, equip mentality, and artless of architecture, thus establishing an integral unity between the principles of the Vitruvian Triad. Thus, the three Vitruvian principles come to unify in architecture which is defined as “the manifestation of truth of human desired life in the work of architecture.” This definition also allows us to assume three fundamental principles for architecture, “truth of human desired life”, “work of architecture” and “manifestation of truth”. These three principles are themselves, in fact, reflections of the three Vitruvian principles.