- 15th century
The origin of the pazo could begin with a primitive medieval fortress surrounded by a preserve, it would consist of two towers joined by a fully crenelated intermediate body. Although the remains that have survived start from the middle of the 15th century at the hands of the first lords of Oca.
- 16th century
In the 16th century, the new owner, María de Neira, built an oratory in honour of Saint Anthony, adjacent to the pazo, which in turn underwent some transformations in the 18th century. Some vestiges remain from this period, such as the facing doors of the entrance hall, carved in 1583 and crowned by the arms of the Neira and Luaces lineages.
- 17th century
The fundamental stage of the remodelling and expansion of the complex began at the end of the 17th century and during the 18th century, following the prototype of the Galician Baroque style. In this way, the old fortress of Oca would end up becoming a magnificent palace.
- 18th century
In the 18th century, Andrés Gayoso and his wife remodelled the façade of the pazo that overlooks the plaza, then a work site, at the end of which they rebuilt the old medieval tower and built other outbuildings.
During the second quarter of the same eighteenth century, his son, Fernando Gayoso Arias Ozores and his wife, continued the remodelling and expansion of the old fortress, building the south wing of the building, with a monumental Baroque Chapel that would replace the old hermitage, also the communication gallery of the chapel with the house-palace, some rooms, the kitchen, "lareira" (fireplace), pantry and the rooms of the butler and the pages were built.
In the following years of the same eighteenth century, Francisco Javier Arias Ozores ordered the construction of the wooden solarium or "wooden corridor" and, later, his brother and successor, Domingo Gayoso de los Cobos, carried out some reforms in the palace's premises. to finish forming the pacega unit through the acquisition of adjoining land and finished walling the entire property.
- 19th century
During the third quarter of the 19th century, the communication staircase of the noble floor of the palace with the patio, the upper gallery and its lower loggia were built. In the surroundings of the landlords, the central fountain, the façade of the sunny (eastern) and other works were carried out in the palace, in accordance with the romantic fashion of those moments, such as the semi circular guest rooms. At the same time the landscaping transformation of the garden will be carried out, to replace the previous formalist garden.
- 20th century
During the 20th century, there will be two stages of interventions. The first one carried out, during the 1920s, by the Marquis of Camarasa Ignacio Fernández de Henestrosa and his wife Blanca Pérez de Guzmán, the restoration phase of certain areas of the old building, such as the wooden staircase to go down to the so-called topped tower, as well as in the installation of the Cillobre portal (brought from another building of the family) and the subsequent opening of the patio, until then closed, by means of a stone staircase decorated with large balls, in addition to giving back to the garden the formal baroque character that possessed in another time.
The second phase of maintenance and restoration of Oca during the same twentieth century continues to this day at the hands of the Foundation of the Ducal House of Medinaceli.