The central room was the "frigidarium", whose high roof was supported by eight giant columns made from Egyptian granite. Walls and floor were made from marble. The hall served a dual purpose: It was a meeting place and transition area for visitors heading for other parts of the bath. It also housed the cold baths, in the form of four pools, two of which were connected to the "tepidarium" and two of which communicated with the "natatio" via some waterfalls. In the middle of the "frigidarium" was another circular pool (now at the Archaeological Museum at Naples) surrounding a fountain. It was flanked by two additional brick pools.