The walls of Elvas are the greatest bulwark fortifications in the world. Part of the historical-cultural set inscribed on the UNESCO World Heritage List as “Border Town of Elvas and trim and its Fortifications” since June 30, 2012.

The walls had the beginning of its construction in the reign of Sancho II, having been made between the 17th and 19th centuries. They have an area of ​​300 hectares and a perimeter ranging from eight to six miles, the largest system bulwark fortifications of the world.

Inside the walls, the city includes large barracks and other military buildings, churches and monasteries. While Elvas vestiges dating back to the 10th century, its fortifications dates from the time of Portugal´s  Restoration of Independence from in 1640.

The fortifications were designed by the Dutch Jesuit priest John Piscásio Cosmander and represent the best example of military fortifications of the Dutch school that survived to the present day. In the complex is included the Amoreira Aqueduct, which was intended to allow to resist  prolonged sieges.