High Quality Content by WIKIPEDIA articles! Xystus was the Greek architectural term for the covered portico of the gymnasium, in which the exercises took place during the winter or in rainy weather, etc. The Romans applied the term to the garden walk in front of the porticoes, which was divided into flower beds with borders of box, and to a promenade between rows of large trees. The term took its name from the Greek word xustos, meaning "smooth", due to the polished floor of the xystus. "Xystus" was used, by extension, to refer to the whole building containing the gymnasium and portico, as in the xysti of Jerusalem and Elis. The Xystus of Jerusalem was a famous building erected in the Judaeo-Hellenistic period probably under Herodian rule.