Running for 5km, the fortifications of Elvas are one of the most accomplished examples of Portuguese military architecture of the 17C. Best explored on foot, they are constructed in accordance with the techniques of the great military engineer Vauban; the fortified gates, the ditches, the curtain wall and the bastions form a defensive system completed to the south by Santa Luzia fort (17C), and, to the north by Graça fort (18C).