Architect Alberto Campo Baeza has always defended the protagonism of the three Vitruvian principles (firmitas, utilitas and venustas) in architecture, and has integrated them in the unique concept of the ´Built Idea´, which entitles even one of his most famous publications. The aim of this article is to analyze how are considered and integrated the vitruvian concepts in the inner world from which Campo Baeza makes up his architecture, recalling some of his most fundamental references. In this work will de demonstrated how the reason, given the coordinates of the most essential themes with which architecture must lead, is a valid way towards beauty in architecture. See the whole publication in the following link: https://www.campobaeza.com/books/nyit/