Thermae would be heated by a log fire before being channelled into the hot bathing rooms. The design of baths is discussed by Vitruvius in "De Architectura". "Thermae, balneae, balineae, balneum" and "balineum" may all be translated as "bath" or "baths", though Latin sources distinguish among these terms. "Balneum" or "balineum", derived from the Greek signifies, in its primary sense, a bath or bathing-vessel, such as most persons of any consequence among the Romans possessed in their own houses, and hence the chamber which contained the bath, which is also the proper translation of the word "balnearium". The diminutive "balneolum" is
Ancient Roman architecture its complex helical structure, was introduced relatively late into architecture. Although the oldest example dates back to the 5th century BC, it was only in the wake of the influential design of Trajan's Column that this space-saving new type permanently caught hold in Roman architecture. Apart from the triumphal columns in the imperial cities of Rome and Constantinople, other types of buildings such as temples, thermae, basilicas and tombs were also fitted with spiral stairways. Their notable absence in the towers of the Aurelian Wall indicates that although used in medieval castles, they did not yet figure prominently in Roman