Within the walls, the town contains extensive barracks and other military buildings, as well as churches and monasteries, some adapted to military functions. Cosmander applied the geometric theory of Marolois to the irregular topography of Elvas, to produce a defensive system considered a masterpiece of its time. Criterion (iv) : Elvas is an outstanding example of a garrison town and its dry-ditched bulwarked defence system, which developed in response to disruptions in the balance of power within 17th century Europe. The Integrated Management Plan for the Fortifications of Elvas (IMPFE) aims to bring all stakeholders together to ensure the integrity of the property and enhance its potential use. The Management Plan will be implemented by the Office for the Fortifications of Elvas within the city of Elvas, once this is appointed by the Mayor.