The most important Orthodox monastery in Candia was that of Saint Catherine of the Sinai, attested already from the Byzantine period. Today, only the katholikon survives, in the form it assumed during the Venetian period. It is a single-aisled, barrel-vaulted church with a transept, formed with lower-roofed lateral wings, and a two-room chapel attached to the north-eastern side, now dedicated to the Holy Ten Martyrs. The sanctuary was originally flanked by quadrangular parabemata, of which only the northern one survives intact. The church displays two construction phases. The original phase, probably dating to the 14th century, includes the sanctuary and the transept, covered with pointed barrel-vaults, as well as the western part of the chapel, roofed with a rib vault. The section of the main church west of the transept, with its ornate relief decoration on the imposts of the buttressing arches, and the eastern room of the chapel with its impressive Renaissance dome, belong to an intervention of 1576, according to an inscription on the western doorway. During the Ottoman period, the church was converted into the mosque of Zulfikar Agha. From 1967 it housed the collection of religious icons and objects of the Archdiocese of Crete. Since 2014 it has functioned as a fully organised museum of religious icons and objects, following the renovation of the exhibition by the Archaeological Service.