The interior of the spaces of the presbytery area and the transept correspond to the volume, as designed by Roger’s original project. he difference between this part of the building and the other, consisting of the
, is the large
, visible in its original height, on the
side, and reduced by a sub-arch on nave side.
The transverse arm must have been the most emblematic place in the Cathedral: in this area, Roger II had the two sarcophagi made, now in Palermo Cathedral, which have left an imprint on the floor. The front of the transept leading into the apsidal spaces is characterised by the typical overlapping columns placed in angular niches .
At the backs of the two walls , which divide the three apses, on the eastern front of the transept, there is a sculptural group of the Annunciation , as well as, a fresco of Madonna Enthroned on the opposite side, evidence of the decorations inserted over time.
The space was originally tripartite due to the presence, in the median area, of marble barriers with mosaic inlays that delimited the choir area.