A frigidarium's a large cold pool to drop into after enjoying a hot Roman bath. The Caldarium and the Tepidarium opened the pores of the skin. The cold water would close the pores. There'd be a small pool of cold water or sometimes a large Swimming pool. An octagonal example measuring over 5m across was excavated at Bax Farm, near Faversham, Kent in 2006. This had a large brick conduit for supplying cold water. The walls were originally decorated with painted plaster, and the floors with colour… (More on Frigidarium)