​XYSTUS, the Greek architectural term for the covered portico of the gymnasium, in which the exercises took place during the winter or in rainy weather; this was known as the ξυρτὁς δρόμος, from its polished floor (ξύειν, to polish). 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.