Leonardo da Vinci (1452-1519) is considered one of the greatest geniuses of the Renaissance. His studies developed advanced ideas for his time, even in its most unknown aspects, such as: architecture, urban planning and restoration. He never studied formally, but he learned everything due to his method of observation, the study of other treatises and especially the group of artists with whom he collaborated. After the study of its codices a great interest and knowledge is detected, related to the design, the structural calculation, the materials and the constructive systems, in such a way that their proposals influenced the architecture of the Renaissance, through the work of other authors of your time. The purpose of this article is to make a critical analysis of its excellent architectural proposal in the cupola of the Duomo of Milan and the reasons why it was not carried out under its name. This proposal is included within a discipline in which it has never been recognized as such, but which demonstrated the same qualities as in other fields where it is recognized prestigiously.