The original church was built in the form of a compact cross-in-square ("Greek cross plan"), a common variation on the standard middle Byzantine church type.
The three apses in the east adjoin directly on the naos, instead of being separated by an additional bay, as was usual in contemporary Byzantine architecture in the Balkans and Asia Minor.
In the first century of its existence the church was expanded in three distinct phases; first through the addition of a narthex to house the tombs of George of Antioch and his wife; next through the addition of a forehall; and finally through the construction of a centrally-aligned campanile at the west.
The campanile, which is richly decorated with three orders of arches and lodges with mullioned windows, still serves as the main entrance to the church.
Significant later additions to the church include the Baroque façade which today faces onto the piazza.
In the late 19th century, historically-minded restorers attempted to return the church to its original state, although many elements of the Baroque modifications remain.

Certain elements of the original church, in particular its exterior decoration, show the influence of Islamic architecture on the culture of Norman Sicily.
A frieze bearing a dedicatory inscription runs along the top of the exterior walls; although its text is in Greek, its architectural form references the Islamic architecture of north Africa.
The recessed niches on the exterior walls are likewise derive from the Islamic architectural tradition.
In the interior, a series of wooden beams at the base of the dome bear a painted inscription in Arabic; the text is derived from the Christian liturgy (the Epinikios Hymn and the Great Doxology).
The church also boasted an elaborate pair of carved wooden doors, today installed in the south façade of the western extension, which relate strongly to the artistic traditions of Fatimid north Africa.
On account of these "Arabic" elements, the Martorana has been compared with its Palermitan contemporary, the Cappella Palatina, which exhibits a similar hybrid of Byzantine and Islamic forms.
The original church was built in the form of a compact cross-in-square ("Greek cross plan"), a common variation on the standard middle Byzantine church type. The three apses in the east adjoin directly on the naos, instead of being separated by an additional bay, as was usual in contemporary Byzantine architecture in the Balkans and Asia Minor. In the first century of its existence the church was expanded in three distinct phases; first through the addition of a narthex to house the tombs of George of Antioch and his wife; next through the addition of a forehall; and finally through the construction of a centrally-aligned campanile at the west. The campanile, which is richly decorated with three orders of arches and lodges with mullioned windows, still serves as the main entrance to the church. Significant later additions to the church include the Baroque façade which today faces onto the piazza. In the late 19th century, historically-minded restorers attempted to return the church to its original state, although many elements of the Baroque modifications remain.
Certain elements of the original church, in particular its exterior decoration, show the influence of Islamic architecture on the culture of Norman Sicily. A frieze bearing a dedicatory inscription runs along the top of the exterior walls; although its text is in Greek, its architectural form references the Islamic architecture of north Africa. The recessed niches on the exterior walls are likewise derive from the Islamic architectural tradition. In the interior, a series of wooden beams at the base of the dome bear a painted inscription in Arabic; the text is derived from the Christian liturgy (the Epinikios Hymn and the Great Doxology). The church also boasted an elaborate pair of carved wooden doors, today installed in the south façade of the western extension, which relate strongly to the artistic traditions of Fatimid north Africa. On account of these "Arabic" elements, the Martorana has been compared with its Palermitan contemporary, the Cappella Palatina, which exhibits a similar hybrid of Byzantine and Islamic forms.
Church of Santa Maria dell'Ammiraglio