Laconicum

The laconicum (i.e. Spartan, sc. balneum, bath) was the dry sweating room of the Roman thermae, contiguous to the caldarium or hot room. The name was given to it as being the only form of warm bath that the Spartans admitted. The laconicum was usually a circular room with niches in the axes of the diagonals and was covered by a conical roof with a circular opening at the top, according to Vitruvius (v. 10), from which a brazen shield is suspended by chains, capable of being so lowered and raised as to regulate the temperature. The walls of the laconicum were plastered with marble stucco and painted blue with gold stars.