The dome and narthex are modern additions.
One of the most important of these is the gum-resin of Narthex asafetida, which grows abundantly in the high and dry plains of Western Afghanistan, especially between Kandahar and Unculti- Herat.
The inner narthex of the church formed a magnificent vestibule 205 ft.
The addition of a narthex before the main front and a vestibule on the northern side brings the whole western arm of the cross to a square on plan.
The western entrance was approached by an ante-church, or narthex (B), itself an aisled church of no mean dimensions, flanked by two towers, rising from a stately flight of steps bearing a large stone cross.
The top of the narthex forms a wide gallery, communicating with the interior at the triforium level.
The narthex and baptistery belong to an earlier period.
The exterior of the choir, with its four radiating chapels, its jutting cornices supported by modillions and columns with carved capitals, and its mosaic decoration of black and white stones, is the most interesting part of the exterior The rest of the church comprises a narthex surmounted by a tower, three naves and a transept, over which rises another tower.