I am just surprised by the answers suggested in this KudoZ, including your own interpretation, Charlotte. Perhaps what you wrote, “I think in this context it is referring to the stonework/masonry, have I understood this correctly?”, is the outcome of your initial interpretation of the term, prior to getting more familiar with the text you are translating.
And I have to say this is not the right approach in my view. It is not the “stonework/masonry” what is meant by “fábricas” here, but the “pottery workshops” themselves of the site being researched. In my view, the “fábricas” simply refer to the workshops where the pottery was produced.

Your text can be found online, although it is not easy at all to download it. In the context provided, “fábricas” is a synonym for “estructuras alfareras”, I believe, i.e. “talleres alfareros/de alfarería”, “pottery workshops”.

I just refer to the introduction of your text, which displays the following explanation (the link cannot be posted, unluckily):

RESUMEN
Las actuaciones arqueológicas realizadas en el área denominada «el Secano», en la Alhambra, nos permitieron iniciar el studio de las estructuras alfareras presentes allí. El proyecto fue diseñado de manera global, se analizó toda el área de carácter artesanal y se incorporaron diferentes técnicas analíticas. En este trabajo presentamos los resultados preliminares de este proyecto.

ABSTRACT
The excavations carried out in the area of El Secano, in the Alhambra, have allowed us to start analysing the pottery workshops located in the area. The project followed a multidisciplinary methodology, examining the whole industrial complex by means of different analytical techniques. This is a report of our preliminary results.


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Note added at 3 days 3 hrs (2023-07-15 12:27:41 GMT)
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Another interesting reference (another context, though):
https://espanafascinante.com/cultura-espanola/ceramica-en-gr...
CULTURA ESPAÑOLA | ARTESANÍA
Alfarería y Cerámica en Granada
(…)
En cuanto a la cerámica de Fajalauza, llamada así debido a los numerosos talleres de alfarería y los hornos que existían junto a la Puerta de la Fajaluza en el barrio del Albaicín de la capital, su origen se remonta del siglo XVI y todavía sobreviven algunos de estos talleres o fábricas como la de San Isidro.