This course is focused on an idea: Europe had a common legal past. In the Middle Ages, the so-called "Ius Commune" was studied in all the universities and it was used by the jurists from around the old continent. This common law transcended national and legal boundaries. For this reason, the history of law in Europe has the same vocabulary, that was created by the "ius commune". This law consisted of Roman, Canon a Feudal law. As the rest, Spain has been part of this European reality. Our juridical past is determined by Europe because Spain has not been an island on the continent. But also, the different local institutions (a kingdom, a principality, a feudal lordship, a monastery) had their own law, with their particularities, the so-called "ius proprium" (particular law). The principal aim of this course will be the knowledge of the common legislation of Europe and the singularities of the "ius proprium". The addition of the "Ius Commune" to the "ius proprium" will show the "system of Ius Commune". Then, it's very important to understand that the big legal categories used in Western Europe had the same origin, the "Ius Commune". Nowadays, if we speak about "property", "obligation", "will", we use the meaning created by "Ius Commune": dominium, obligatio, testamentum.