The dome and narthex are modern additions.
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.
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 top of the narthex forms a wide gallery, communicating with the interior at the triforium level.
In the centre of this court stands the catholicon or conventual church, a square building with an apse of the cruciform domical Byzantine type, approached by a domed narthex.