Since the Muslim occupation of Ialbax by king Sancho II in 1230 and until its was promoted to city in 1513, the development of Elvas was solid, favored for its relevant geographical position which over the centuries gave it an outstanding military preponderance, reflected in the construction of fortification lines and military buildings. In the second half of the fourteenth century, another fortification was added to the two Muslim walls, with 11 gates and 22 towers, which became forever represented in the drawings of Duarte de Armas.
Throughout the seventeenth and eighteenth centuries, Elvas became a war arena of great magnitude, with a variety of barracks, bunkers, bases (provisions warehouse), depot (artillery warehouse), military hospital, military base, house of the governor and war council, reflecting the evolution and consolidation of the army.
The seventeenth-century walls that surround the Historic Centre are a notable worldwide example of the First Dutch method of fortification which, along with the Forts of Santa Luzia, Graça, São Pedro, São Mamede, São Domingos and Piedade, and the Amoreira Aqueduct, were worldwide recognized and valued on June 30th, 2012, being classified as World Heritage by UNESCO.
The set of bastion fortifications of Elvas is the world's largest entrenched camp of land bastion fortifications with a dry moat, for the sum of the internal areas of its fortifications, for the total perimeter of covered paths, for the total number of bastions and half-bastions of the compounds and for the unusual integrity, good condition and authenticity of its materials and construction techniques, thus representing a significant moment in human history in the field of Military Architecture and History.