The preserved and visible remains in this location correspond to an old Roman Factory from the 4th and 5th centuries. This was where fish was cleaned, cut up and salted for making salt fish and sauces, such as the famous garum.
The factory extended below the existing streets and land adjacent to the museum. The preserved structures date mainly to the period between the mid-4th and 5th centuries, a flourishing period for these industries along the Murcian coast, although it is likely the origins of the installation date back to an earlier era.
The Roman fish salting and sauce industry were already starting to proliferate in the 1st century BC along the coast of the south of the peninsular and North Africa, continuing and strengthening a tradition begun in the Phoenician and Punic period. These kinds of companies formed – along with wine, oil and mining – the basic pillars on which were based the economy and external and interprovincial trade. The products form the peninsular salting factories acquired a wide fame and would become essential in all the empire’s kitchens. Production and marketing were in the hands of the big companies and societies, making authentic “brands” or “certificates of origin”, such as the so-called “garum sociorum” from the south-east of the Iberian peninsular, the memory of which classic sources has left us, famous throughout the empire.
The chosen site for these kinds of installations was usually an area close to the port to facilitate the transport of the fish to the factory. The common characteristic elements of all these industries were the basins, seafood tanks or salting tanks, made from lime mortar and stone, lined inside to make them impermeable with successive layers of opus signinum (lime, stone and crushed pottery), lined up, excavated in the earth and quadrangular. In these basins was where the fish was crushed with salt, being left to a fermentation process with lasted from 20 days to three months. The same receptacles were used for salting the flesh of the fish (salsamenta) as well as for making the different fish sauces, of which the most famous and sought after was garum.
Another series of rooms are the halls for carving up, cleaning and storage. The work rooms which required constant cleaning were usually paved with opus signinum, sometimes with a slight incline to facilitate the evacuation of water and the residue this activity produced. Other rooms, such as those for storage, had simple lime floors. The process required the building to have protective cover to prevent excessive evaporation from the direct action of solar rays or the desalination of the water from the rain, but also ventilation in order to control the entrance of the right amount of heat and evaporation.