Chapels were among the important types of buildings that evolved during the first four centuries of organised Christianity in the West. They were originally developed in connection with the cult of the saints, commemorating both their gravesites and their places of martyrdom. But the chapels rapidly found other uses among the ever-expanding Christian population as places of prayer and pilgrimage, and were chosen by the faithful for their own burial beside the saints.

With little in the way of contemporary written records, the decorative programme of each chapel is now often the only...