On Architecture

3. But on the outside, let three colonnades be arranged, one as you leave the peristyle and two at the right and left, with running-tracks in them. That one of them which faces the north should be a double colonnade of very ample breadth, while the other should be single, and so constructed that on the sides next the walls and the side along the columns it may have edges, serving as paths, of not less than ten feet, with the space between them sunken, so that steps are necessary in going down from the edges a foot and a half to the plane, which plane should be not less than twelve feet wide. Thus people walking round on the edges will not be interfered with by the anointed who are exercising.

4. This kind of colonnade is called among the Greeks custo/s, because athletes during the winter season exercise in covered running tracks. Next to this “xystus” and to the double colonnade should be laid out the uncovered walks which the Greeks term paradromi/des and our people “xysta”, into which in fair weather during the winter, the athletes come out from the “xystus” for exercise. The “xysta” ought to be so constructed that there may be plantations between the two colonnades or groves

1. THE subject of the usefulness of harbours is one which I must not omit, but must explain by what means ships are sheltered in them from storms. If their situation has natural advantages, with projecting capes or promontories which curve or return inwards by their natural conformation, such harbours are obviously of the greatest service. Round them, of course, colonnades or shipyards must be built, or passages from the colonnades to the business quarters, and towers must be set up on both sides, from which chains can be drawn across by machinery.