The figure of Xoán Arias, of Galician origin, is closely associated to an intense construction activity around the Romanesque cathedral of Santiago. He commissioned the construction of a cloister and a new archbishop’s palace, thus completing the complex round the cathedral. He also collaborated with the local bourgeoisie in the construction of a new Gothicchevet, which meant a significant increase in size.
He was apparently behind the creation of the castle of Rocha Forte or, at least, of its first architectural version, by establishing the the location and layout of the fortress. We cannot pinpoint the mark he left in its architecture as the castle underwent many alterations in the following centuries.
He played a very outstanding role in the administration of the diocese. As to the city, he had a tense (albeit sustainable) relationship with the bourgeoisie that deteriorated towards the final stage of his office.