This is the cold room, a place from where everyone should pass, with its two sides elevated over, the pavement giving a better sense to the users and protecting them from the humidity of the floor.
The access door towards this room had a double-door system mechanism with an automatic closing due to the gravity. On each side of the door, there were two swings which due to this system of a two-double door; a watertight security could be achieved in both compartments of the room.
The cover of the room is formed by a groin vault lowered with four narrower segments which come out from round arches that substitute the squinches. The cold room is the first humid room in the complex of the Baths.
In the South of the frigidario we can find a double door, the same as the one in the locker room (apoditerio) that allows us to reach the warm room or the tepidario