Its construction took from 1390 until the mid 16th century, combining Gothic and Manueline architectural styles.
The third and definitive Guarda Cathedral started being built in 1390 under bishop Vasco de Lamego, during the reign of King John I.
In the period from 1504 to 1517, under bishop Pedro Gavião, the pace of the works increased and the cathedral was almost completed.
The Manueline style - a Portuguese mix of Gothic and early Renaissance - was the dominant influence in this second building stage, as attested by the decoration of the windows of the nave and transept, the decorated rib vaulting of the transept, some spiralling columns of the nave as well as the main portal, similar to the Manueline portal of Saint Michael's Chapel of Coimbra University.
Despite the artistic value of some of these additions - like the Baroque organ - all were removed during a renovation carried out in 1898 by architect Rosendo Carvalheira, which aimed at restoring the cathedral to its primitive, Gothic/Manueline appearance.