Interamnium of the Romans, a town of Estremadura in Spain, on the left bank of the Tagus, with 4273 inhabitants. Alcantara (Arabice, Al Kantrah, i.e. the bridge), derived its name from the magnificent Roman bridge which spanned the Tagus at this point; and which was erected, according to the inscription, in A.D. 104, at the joint expense of the several towns therein mentioned, in honour of the Emperor Trajan, who was a native of Spain. This noble monument of antiquity was injured by the English, and afterwards, with gratuitous barbarism, blown up by the French general Victor, during the campaign of 1809. It was repaired with timber in 1818, and again burnt in 1836 to prevent the passage of the Carlist troops. Lat. 39. 41. N. Long. 6. 44. W.

Knights of Alcantara, one of the five military orders of Spain, which took its name from the above-mentioned city. They make a very considerable figure in the history of the expeditions against the Moors. The knights of Alcantara make the same vows as those of Calatrava, and are only distinguished from them by this, that the cross fleur-de-lis, which they bear over a large white cloak, is of a green They possess 37 commanderies. By the terms of the surrender of Alcantara to this order, it was stipulated that there should be a confraternity between the two orders, with the same practices and observances in both; and that the order of Alcantara should be subject to be visited by the grand master of Calatrava. But the former soon released themselves from this engagement, on pretence that their grand master had not been called to the election of that of Calatrava, as had been likewise stipulated in the articles. After the expulsion of the Moors, and the taking of Granada, the sovereignty of the order of Alcantara and that of Calatrava was settled in the crown of Castile by Ferdinand and Isabella. In 1540 the knights of Alcantara sued for leave to marry, which was granted them.