The underground part of the Castle used to house one of the service areas, notably the kitchen, a prison (given that the feudal lords were responsible for delivering justice), and a storeroom area for keeping grain and other agricultural produce. It should be borne in mind that the lords of Torredembarra, as in other areas, used to receive part of their feudal rights in kind, so they needed somewhere in their residence to store all these products.
In the kitchen you can still see the base of the large fireplace that once dominated the room.