After the coronation of 1130, Roger II ordered the construction of the Palace Chapel. Architecturally and decoratively, it represents a fusion of different cultures and religions, as Byzantine, Islamic, and Latin craftsmen were involved in its creation.

The church, dedicated to Saint Peter the Apostle, features a layout where Latin and Byzantine elements coexist, creating a unique architectural blend enhanced by its mosaic decorations. The dome is dominated by the image of Christ Pantocrator, which is also repeated in the apse’s central semi-dome. Among the oldest mosaics in the presbytery are scenes from the New Testament, including the Baptism of Christ—an exceptional work noted for its stylistic refinement.