The exterior appearance of the church is certainly disappointing, but within it is, beyond all question, one of the most beautiful creations of human art. On a large scale, and in magnificent style, it combines the attractive features of a basilica, with all the glory of an edifice crowned by a dome. We have here a stately hall, 235 ft. N. and S., by 250 ft. E. and W., divided by two piers and eight columns on either hand into nave and aisles, with an apse at the eastern end and galleries on the three other sides. Over the central portion of the nave, a square area at the angles of which stand the four piers, and at a height of 179 ft. above the floor, spreads a dome, 107 ft. in diameter, and 46 ft. deep, its base pierced by forty arched windows. From the cornice of the dome stretches eastwards and westwards a semi-dome, which in its turn rests upon three small semi-domes. The nave is thus covered completely by a domical canopy, which, in its ascent, swells larger and larger, mounts higher and higher, as though a miniature heaven rose overhead. For lightness, for grace, for proportion, the effect is unrivalled. The walls of the building are reveted with marbles of various hues and patterns, arranged to form beautiful designs, and traces of the mosaics which joined the marbles in the rich and soft coloration of the whole interior surface of the building appear at many points. There are forty columns on the ground floor and sixty in the galleries, often crowned with beautiful capitals, in which the monograms of the emperor Justinian and the empress Theodora are inscribed. The eight porphyry columns, placed in pairs in the four bays at the corners of the nave, belonged originally to the temple of the sun at Baalbek. They were subsequently carried to Rome by Aurelian, and at length presented to Justinian by a lady named Marcia, to be erected in this church "for the salvation of her soul." The columns of verde antique on either side of the nave are commonly said to have come from the temple of Diana at Ephesus, but recent authorities regard them as specially cut for use in the church. The inner narthex of the church formed a magnificent vestibule 205 ft. long by 26 ft. wide, reveted with marble slabs and glowing with mosaics.