It was declared a National Monument in 1931. It was the second convent the Dominicans established upon reaching Galicia. It was constructed between the 13th and 14th centuries. The basilica design church is considered one of the best examples of Galician Gothic mendicant. The historiated capitals with plant, animal and geometric motifs are noteworthy. Its sepulchres (13th to 16th centuries) and its various altarpieces and images (15th to 18th centuries) are also of great value.
On the main façade we can see the coat of arms of the Sarmiento family, the Royal Coat of Arms of Castile and León and the coat of arms of Friar Alfonso de Cusanca.
The convent was run in the 14th century as a Study House, with chairs of Moral Theology and Grammar.
Initially this convent, one of the most active in Galicia, was set up in honour of Saint Mary of Valparíso. From the 17th century, the Virgin of the Portal began to be venerated, so that finally the Church of the Portal was constructed next to it.