For years this construction remained in the shadow  of the Cappella Palatina wanted by Ruggero II and is a monument known only by the few. The name of Santa Maria delle Grazie comes after the insertion of the altarpiece depicting the iconography that bears the same name dating back to the amplifications made into the palace during the Spanish period.

The place often named the “cripta”, because is located below the Cappella Palatina, is in fact a lower church, as it is not located below the cortile Maqueda.

The nucleus consists of three complementary parts: to the east we find a chapel with three naves divided by two columns and covered by a cross vault (Chiesa Santa Maria delle Grazie), to the west a rectangular hall with a barrel vault (area in which in 1166 was placed the sarcophagus of Guglielmo I ) and finally a walkway that surrounds the structure from all four sides.

The church was also used as burial place for prominent individuals such as Vicerè Emanuele Filiberto di Savoia, who died for the plague in 1624.