We have little information on the construction of the castle and mostly is indirect or even confusing. But there is consensus on attributing the fortress to Archbishop Xoán Arias. This appears in later documents but, most importantly, texts of his time mention an archbishop’s residence at Rocha Forte.
Unlike his successors in the office, Archbishop Xoán Arias did not have (that we know of) chroniclers that kept record of his decisions while in office. But we do have other documents where the existence of the castle is recorded. The first mention appears in 1253, in a ruling by Afonso X by reason of a dispute between the archbishop and the City Council of Santiago on the exercise of justice and the innovations that Xoán Arias wished to introduce:
«Otrosy, querelaron los pesoneros sobredichos del Conceyo de Santiago que se alguno de la uila ha preyto con otro, primeyramiente es tenudo de Responder por ante los juyzes de la uila; et agora que uos, que ante que nenhun juyzo sea dado, aquelos que queredes sacadelos delante los juyzes, et fazedelos yr ante uos a Rocha forte; et que en esto le quebrantades su uso et so custumbre; lo que nunca fué».
Fueros municipales de Santiago y de su tierra, Antonio López Ferreiro, p 238.
«The said councillors of the city council of Santiago argued that if anyone from the town had a dispute with another, they should go first to the magistrates of the city to settle their differences and now you, before any judgment is given, when you so wish, force them to ignore the judges and make them appear before you at Rocha Forte; and by so doing you go against custom and usage; this has never been seen».
We also know that the castle was inhabited in 1255, as stated in the chapter constitutions on the choir and the chapter:
«Statuimus etiam de personis et canonicis, maniapaniis, duplaris morantibus nobiscum apud Rocham Fortem, quod eant ad processiones diebus dominicis solemnitatibus. Et si yuerint ad Ciuitatem Compostellanam ante prandium veniam ad maiorem missam. Si post prandium veniam ad uesperas sive completorium in quadragessima».
Published in Historia de la Santa A. M. Iglesia de Santiago de Compostela, Antonio López Ferreiro, 1898, V, num XXX, p 81.
«We also establish that the persons, canons, the prebendary and labour men who live with us at Rocha Forte must attend the processions on Sundays as well as on solemn dates. And should they come to the city of Santiago before dinner, they should attend the Main Mass; and should they come to the city of Santiago after dinner should do so at vespers or compline during Lent».
Another reference is found in the will of Xoán Arias, which is dated 1266, and where he mentions the Castellum de Rocha Forte as archbishopric property.