The Lethes Theater is part of the European Route of Historic Theaters. Originally built in 1605 as the College of St. James Major of the Society of Jesus, it was founded by the then Bishop of the Algarve D. Fernando Martins Mascarenhas. This little gem of architecture was built following the end of the 1830/33 civil war between liberals and absolutists. Hence the name of the mythical Roman river of oblivion, since it was a matter of forgetting, through art, culture and entertainment, the wounds and hatreds of conflict. The opening of the Lethes Theater took place on April 4, 1845, in association with the commemorations of Queen Maria II's birthday. It is currently part of The Algarve Theater Company - ACTA as a resident structure.