The Martorana Also Co-Cathedral of St. Mary of the Admiral (Italian: Concattedrale Santa Maria dell’Ammiraglio) is the seat of the parish of San Nicolò dei Greci (Albanian: Klisha e Shën Kollit së Arbëreshëvet), a Co-cathedral overlooking the Piazza Bellini in Palermo, Sicily, southern Italy. The church belongs to the Eparchy of Piana degli Albanesi of the Italo-Albanian Catholic Church, a diocese which includes the Albanian communities in Sicily who officiate the liturgy according to the Byzantine Rite in the ancient Greek language.
The church is characterized by the multiplicity of styles that meet, because, with the succession of centuries, it was enriched by various other tastes in art, architecture and culture. Today, it is, in fact, as a church-historical monument, the result of multiple transformations, also subject to protection.
The name ("admiral") derives from the founder of the church, the Greek admiral and principal minister of King Roger II of Sicily, George of Antioch. The foundation charter of the church (which was initially Eastern Orthodox), in Greek and Arabic, is preserved and dates to 1143; construction may already have begun at this point. The church had certainly been completed by the death of George in 1151, and he and his wife were interred in the narthex. In 1184 the Arab traveller Ibn Jubayr visited the church, and later devoted a significant portion of his description of Palermo to its praise, describing it as "the most beautiful monument in the world." After the Sicilian Vespers of 1282 the island's nobility gathered in the church for a meeting that resulted in the Sicilian crown being offered to Peter III of Aragon.