e
a palaestra, the peristyle ought to be laid out as described above.

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.

[Illustration: I. THE PALAESTRA AT OLYMPIA; II. THE GREEK PALAESTRA
ACCORDING TO VITRUVIUS]

4. This kind of colonnade is called among the Greeks [Greek: xystos],
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 [Greek: paradromides] 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 of plane trees, with walks laid out in them among
the trees and resting places there, made of "opus signinum." Behind the
"xystus" a stadium, so designed that great numbers of people may have
plenty of room to look on at the contests between the athletes.

I have now described all that seemed necessary for the proper
arrangement of things within the city walls.

CHAPTER XII

HARBOURS, BREAKWATERS, AND SHIPYARDS

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.

2. But if we have a situation without natural advantages, and unfit to
shelter ships from stor