One half of the space, perhaps more, would be occupied by large open courts, paved probably with marble, surrounding the various blocks of buildings and separating them from one another.

The buildings themselves may be conjectured to have resembled those of the Achaemenian monarchs at Susa and Persepolis, with the exception, apparently, that the pillars, which formed their most striking characteristic, were for the most part of wood rather than oL stone.

Polybius distinguishes the pillars into two classes, those of the main buildings, and those which skirted the courts, from which it would appear that at Ecbatana the courts were surrounded by colonnades, as they were commonly in Greek and Roman houses.

These wooden pillars, all either of cedar or of cypress, supported beams of a similar material, which crossed each other at right angles, leaving square spaces between, which were then filled in with woodwork.

Above the whole a roof was placed, sloping at an angle, and composed (as we are told) of silver plates in the shape of tiles.