Vauban’s work is generally viewed as divided into two parts: the "Traité de l’Attaque des Places" (Treatise on Attacking Fortified positions) and the Dîme Royale (royal tax) project. This paper points out the profound unity of his work from both a methodological and political viewpoint. Regardless of the field, Vauban, as a scientist, starts with a meticulous observation in the form of rigorous inquiry. He then proceeds to make numerous experiments, after which he is able to formulate theories on fortifications and taxes. His thinking is driven by action. As an economist, Vauban is preoccupied with saving (state) money and (military) men. As a sociologist, he aims to improve welfare. As a geographer, he intends to optimize the use of French territory (known as the "pré carré"). Finally, how his work has been considered assessed by contemporaries, historians, and economists is reviewed along with the reasons for its originality. JEL: B11, N43