Churches of the Byzantine time, of the Venetian period, as well as later ones are still preserved today, in different parts of the city, each one having its own history, denoting the deep religious belief of the people of Heraklion during their long history. Some of the churches, like the church of St. Marc is used today as an exhibition place, while in the church of St. Aikaterini of Sinai, art works of the Cretan school of iconography are exhibited along with ecclesiastical vessels, books, sacerdotal vestments and frescoes.