noun. In a Greek church, the outer narthex or vestibule, in case there were two, as in the church of St. Sophia in Constantinople, the inner narthex being called the esonarthex.

noun. , (Christianity) The space anterior to the narthex of a church, sometimes roofed-over as with a porch, but more often an enclosed courtyard; in antiquity, the courtyard where catechumens were permitted to be close to the Eucharist, but forbidden to see it celebrated.

"Parallel to the esonarthex is the exonarthex, with pictures from the life of Christ, concentrating on his infancy."