There can be little doubt but that both the porches, and the great central pillar-cluster, were roofed in. The double-bull and double-griffin capital are exactly suited to receive the ends of beams, which would stretch from pillar to pillar, and support a roof and an entablature. [PLATE L., Fig.1.] We may see in the entrances to the royal tombs the true use of pillars in a Persian building, and the character of the entablature which, they were intended to sustain, Assuming, then, that both the great central pillar phalanx and the three detached colonnades supported a roof, the question arises, were the colonnades in any way united with the main building, or did they stand completely detached from it? It has been supposed that they were all porticos _in antis_, connected with the main building by solid walls--that the great central column-cluster was surrounded on all sides by a wall of a very massive description, from the four corners of which similar barriers were carried down to the edge of the terrace, abutting in front upon the steps of the great sculptured staircase, and extending eastward and westward, so as to form the antce of an eastern and a western portico. In the two corners between the northern in _antae_ of the side porticos and the _antae_ of the portico in front are supposed to have been large guard-rooms, entirely filling up the two angles. The whole building is thus brought into close conformity with the “Palace of Xerxes,” from which it is distinguished only by its superior size, its use of stone pillars, and the elongation of the tetrastyle chambers at the sides of that edifice into porticos of twelve pillars each. [Illustration: PLATE L.]