The hexagonal ciborium (vaulted altar canopy) stood in the baptistery next to the Novigrad cathedral. Its ancient appearance was recreated in a drawing by L. Dufourny (1754-1818) who had found it in a dilapidated condition. Thus the reconstruction of the fragmentary ciborium is not entirely univocal.

The inscription along its arches refers to Bishop Mauritius, who commissioned the ciborium. As Istrian bishop, Mauritius is mentioned in a letter by Pope Adrian I to Charlemagne (dated to between 776 and 780), which also sheds light on the time of origin of the ciborium. The composition and the choice of motifs in the relief decorations are characteristic of ciboria in general, but above all of those in the Veneto and Friuli regions.

The Mauritius Ciborium, without equal in Istria, was presumably produced in a workshop in Cividale, and represents the last echo of the "Liutprand Renaissance", the Lombard art at the new Carolingian court.