On the side of the dome, east and west, are two half-domes, which crown apsidal walls. Other small apses are domed over at lower levels, and vaulted aisles of two stories run round the higher portions of the building, the whole forming almost a cube-like shape. After Constantinople was captured by the Turks (A.D. 1453), Santa Sophia was converted into a mosque and four minarets, or Moslem towers, were added to its outer angles. The interior of this church, besides the stupendous effect of its unrivalled architectural construction, has its added beauties and splendour in its inlaid marbles, its richly carved cornices and arcades (Fig. 335), and its vaults and domes glittering with gold mosaics of cherubim, and dignified though gaunt and archaic figures. In the capitals of the columns was used the sharply-edged and undercut acanthus foliage, more in accordance with the old Greek type than the Roman, but have a distinctly Byzantine character of its own. Sacred signs, emblems, and birds were often introduced into the capitals; the general shape of the latter was a cubical form, the four faces slanting inwards from above, this form giving a decided appearance of great supporting and sustaining power (Figs. 336 and 338). Sometimes they were bossed out, and often contained the elements of the Ionic and Corinthian orders (Figs. 336, 337, 339). The wedge-shaped portion on the top of the capital is an ugly but distinctive feature of the Byzantine style (Fig. 338). [Illustration: Fig. 335.—Cornice from Santa Sophia.] The splendour and magnificence of the decoration in Byzantine churches is proverbial: the columns were often of porphyry and serpentine marble, and the supports to the altar canopy (_baldacchino_), the screen (_iconostasis_) and the pulpit (_ambo_) were often inlaid with gold, silver, and precious stones. The altar itself was a gorgeous piece of workmanship, resplendent with gold and enamels, decorated with hanging lamps, vases, and candlesticks, all wrought in precious metal work, though the actual design and workmanship was rough and less refined than antique work. [Illustration: Fig. 336.—Capital from Santa Sophia, showing the bossing-out of the ornament.] [Illustration: Fig. 337.—Capital from St. Demetrius at Salonica.] [Illustration: Fig. 338.—Capital from St. Demetrius.]