"It is distinguished by indescribable beauty, excelling both in its size, and in the harmony of its measures, having no part excessive and none deficient; being more magnificent than ordinary buildings, and much more elegant than those which are not of so just a proportion. The church is singularly full of light and sunshine; you would declare that the place is not lighted by the sun from without, but that the rays are produced within itself, such an abundance of light is poured into this church. _The Apse._--Now the head (πρόσωπον) of the church (that is to say the part towards the rising sun, where the sacred mysteries are performed in honour of God) is built as follows. The building rises from the ground not in a straight line, but setting back somewhat obliquely, it retreats in the middle into a rounded form which those who are learned in these matters call semi-cylindrical, rising perpendicularly. _Apsoid and Semidome._--The upper part of this work ends in the fourth part of a sphere, and above it another crescent-shaped (μηνοειδές) structure is raised upon the adjacent parts of the building, admirable for its beauty, but causing terror by the apparent weakness of its construction; for it appears not to rest upon a secure foundation, but to hang dangerously over the heads of those below, although it is really supported with especial firmness and safety. _Exedras._--On each side of these parts are columns standing upon the floor, which are not placed in a straight line, but arranged with an inward curve of semicircular shape, one beyond another like the dancers in a chorus. These columns support above them a crescent-shaped structure. Opposite the east wall is built another wall, containing the entrances, and upon either side of it also stand columns, with stonework above them, in a half-circle exactly like those previously described. _Great Piers and Arches._--In the midst of the church are four masses of stone called piers (πεσσούς), two on the north and two on the south sides, opposite and alike, having four columns in the space between each pair. These piers are formed of large stones fitted together, the stones being carefully selected, and cleverly jointed into one another by the masons, and reaching to a great height. Looking at them, you would compare them to perpendicular cliffs. Upon them, four arches (ἀψῖδες) arise over a quadrilateral space. The extremities of these arches join one another in pairs, their ends resting upon the piers, while the other parts of them rise to a great height, suspended in the air. Two of these arches, that is those towards the rising and the setting of the sun, are constructed over the empty air, but the others have under them some stonework and small columns. _Dome and Pendentives._--Now above these arches is raised a circular building of a curved form through which the light of day first shines; for the building, which I imagine overtops the whole