The eastern bay of the nave is square on plan, bounded by semicircular arches, all extended so as to form short barrel vaults. The western arch is joined to the eastern arch of the western bay, thus forming a short barrel vault common to both bays. The vault to the east runs to the semi-dome of the apse; whilst the vaults to north and south, like the corresponding vaults in the western bay, extend to the outer walls and cover the eastern portions of the aisles and galleries. Above the supporting arches regular pendentives are formed, and above these there is a drum carrying a dome. The apse to the east of the nave is semicircular within and covered by a semi-dome.
Between that semi-dome and the eastern barrel vault of the nave a break is interposed, giving the bema arch two orders or faces, with their external and internal angles rounded off, and the whole surface of the semi-dome and of the bema arch is covered with mosaic. At one time the mosaic extended also over the surface of the barrel vault. The decoration in the semi-dome consists of a large cross in black outline upon a gold ground; below the cross there are three steps set upon a double band of green that runs round the base of the semi-dome. A geometrical border bounds the semi-dome, and then comes the following inscription, an extract from Psalm lxv. verses 5, 6 (the lxiv. in the Septuagint version), on the inner face of the arch:
(ΔΕΥΤ ΕΙ)CΟΜΕΘΑ ΕΝ ΤΟÎC ΑΓΑΘΟÎC ΤΟΥ ΟÎΚΟΥ CΟΥ, ĀΓΙΟC Ο ΝΑΟC CΟΥ ΘΑΥΜΑCΤΟC ΕΝ ΔΙΚΑΙΟCΥΝΗ ΕΠΑΚΟΥCΟΝ ΗΜΩΝ Ο Θ[ΕΟ]C Ο C[ΩΤ]ΗΡ ΗΜΩΝ Η ΕΛΠΙC ΠΑΝΤΩΝ ΤΩΝ ΠΕΡΑΤΩΝ ΤΗC ΓΗC ΚΑΙ ΤΩΝ ΕΝ ΘΑΛΑCCΗ ΜΑΚ(ΡΑ)[Ν].
(Come we will go?) in the good things of thy house. Holy is thy temple. Thou art wonderful in righteousness. Hear us, O God our Saviour; the hope of all the ends of the earth and of them who are afar off upon the sea.
The letters enclosed within curved brackets and the accents[141] above them are paint only; the letters within square brackets are not in the inscription, but are supplied where evident contractions render that course necessary. The remaining letters are in unrestored mosaic.
Probably (Δεῦτ᾿ εἰς) όμεθα is a mistake of the restorer for the word πλησθησόμεθα in the original text. 'We shall be filled with the goodness (or the good things) of thy house.'
Three other geometrical patterns in mosaic succeed, after which follows a broad wreath of foliage on the outer face of the bema arch and the words:
(Ο Ο)ΙΚΟΔΟΜΩΝ ΕΙC Τ(ΟΝ ΟΙΚΟΝ CΟΥ ΚΑΙ) ΑΝΑΒΑCΙΝ ΑΥΤΟΥ, ΚΑΙ ΤΗΝ ΕΠΑΝΓΕΛΙΑΝ (ΤΟΥ ΗΑΓΙΟΥ ΠΝΕΥΜΑΤΟC ΕΥ ΗΜΑC ΗΛΠΕΙCΑΜΕΝ ΕΙC ΤΟ Ο)ΝΟΜΑ Α(ΥΤΟΥ).
The mosaic above the crown of the semi-dome has been injured and restored imperfectly in plaster, paint, and gilt. Hence the large black patch in it which includes the upper arm of the cross.
The letters enclosed within curved brackets are in paint and are manifestly the work of a restorer who has spoiled the grammatical construction of the words and obscured the meaning of the inscription. The remaining letters are in unrestored mosaic.