Another century probably elapsed before Khosru (Nushirvan) commenced the most daring, though certainly not the most beautiful ever attempted by any of his race; for to him we must ascribe the well-known Tâk Kesra (Woodcuts Nos. [263], [264]), the only important ruin that now marks the site of the Ctesiphon of the Greeks—the great Modain of the Arabian conquerors.
As it is, it is only a fragment of a palace, a façade similar in arrangement to that at Firouzabad, but on a much larger scale, its width being 312 ft., its height 105 to 110, and the depth of the remaining block 170 ft. In the centre is a magnificent portal, the Aiwan, or Throne room of the palace, vaulted over with an elliptical barrel vault and similar to the smaller vestibules of Serbistan and Firouzabad; the lower portion of the arch, the springing of which is about 40 ft. from the ground, is built in horizontal courses up to 63 ft. above the ground, above which comes the portion arched with regular voussoirs; by this method not only was an enormous centering saved, but the thrust of that portion built with voussoirs was brought well within the thickness of the side walls. It is probable that the front portion of the arch, about 20 ft. in depth, was built on walls erected temporarily for that purpose; the remainder of the vault, however, was possibly erected without centres, the bricks being placed flatwise and the rings being inclined at an angle of about 10° towards the back of the front arch. The tenacious quality of the mortar was probably sufficient to hold the bricks in their places till the arch ring was complete, so that the centering was virtually a template only, giving the correct form of the ellipse, and constructed with small timbers so as to save expense. A similar method of construction was found by Sir Henry Layard in the drain vaults at Nimroud, and it exists in the granaries built by Rameses II. in the rear of the Rameseum at Thebes. The lower or inner portion of the great arch is built in four rings of bricks or tiles laid flatwise, two of which are carried down to the springing of the whole arch: above these in the upper portion of the arch comes a ring 3 feet in height, regularly built in voussoir-shaped bricks breaking joint, on the surface of which are cut a series of seventeen foils, the whole being crowned by a slightly projecting moulding. These have nothing to do with the construction, and are simply a novel method of decoration carved after the arch was built.
263. Plan of Tâk Kesra at Ctesiphon. (From Flandin and Coste.) Scale 100 ft. to 1 in.
264. Elevation of Great Arch of Tâk Kesra at Ctesiphon. Scale 50 ft. to 1 in.
The wall flanking the great arch on either side is decorated with buttress shafts and blind arches, which are partially constructive, and intended to support and strengthen those portions of the wall which were simply screens, or to resist the thrust of the walls of the vaulted chambers behind, consisting of one storey only. Decoratively they divide up the front and were apparently introduced in imitation of the great Roman amphitheatres. The position occupied by these semi-detached shafts on the first storey (resting on the ledge left by the greater thickness of wall of the lower storey), which are not in the axes of those below, proves that the Sassanian architect thought more of their constructive value as buttresses, than of their architectural value as superimposed features.
265. Sketch Plan of Palace at Mashita.
Though it may not perhaps be beautiful, there is certainly something grand in a great vaulted entrance, 72 ft. wide by 85 ft. in height and 115 in depth, though it makes the doorway at the inner end and all the adjoining parts look extremely small. It would have required the rest of the palace to be carried out on an unheard-of scale to compensate for this defect. The Saracenic architects got over the difficulty by making the great portal a semidome, and by cutting it up with ornaments and details, so that the doorway looked as large as was required for the space left for it. Here, in the parent form, all is perfectly plain in the interior, and painting alone could have been employed to relieve its nakedness, which, however, it never would have done effectually.[[205]]