About 12 kilometers to the east of the Spanish border is the fortified Portuguese town of Elvas. Elvas was Portugal’s chief frontier fortress south of the Tagus during the Portuguese Restoration War. From the 17th to the 19th Centuries the area was heavily fortified to protect against Spanish invasion. When construction was completed, two forts and several fortified hilltops formed a defensive perimeter around the walled town.
Elvas’s fortifications held against sieges by the Spanish in 1658, 1711 and 1801. Ultimately the garrison town fell to the French in March 1808 during the Napoleonic Wars. Five months later, after the Convention of Sintra, Elvas was back in Portuguese hands.