_Boundaries._--Probably the fullest and clearest account of the approach to the church through the Augusteum is given by the Spanish ambassador Clavijo, who was at Constantinople in 1405, at a time when many of the buildings in the precincts had been destroyed. In a court in the front of the church, he saw “nine very large columns of white marble,” and he was told that before his time a palace had been here, where the patriarch met the canons in chapter. “And in the same place before the church stands a stone pillar of marvellous height, on the top of which is a horse of copper as large as four horses put together; on the horse was an armed knight with a great plume on his head like a peacock’s tail. The horse has chains of iron round its body secured to the column to prevent it from falling, or being moved by the wind. The horse is very well made, and one fore and one hind leg is raised, as if it were in the act of prancing. The knight, on its back, has his right arm raised, with the hand open, while the reins are held with the left hand. This marvellous horse is said to have been placed here by the Emperor Justinian, who erected the column. At the entrance to the church under an arch in front of a gate, is a place adorned with four columns, and below is a little chapel very rich and beautiful. And beyond this chapel is the gate to the church covered with bronze very great and high; beyond again is a little court surrounded by high galleries [horologium?]. Afterwards there was another gate of bronze [the south porch]. Beyond this gate there is a ‘nave’ vast and high, with a ceiling of wood [the exonarthex]. And on the left hand there is a cloister very large, and beautiful [the atrium], with many stones of jasper of infinite variety of colour. On the right hand under the said nave-covered as I have said--and after the second gate, you arrive at the body of the church, which has five doors, high and large, covered with bronze, of which that in the middle is the greatest.”[306] The present south porch we should suppose is the pronaos mentioned by Nicetas as that where the Archangel Michael stood on guard. The exonarthex is now vaulted, but not covered with mosaic; it is bare and rough, and it seems possible that at one time there may have been a ceiling of wood.