The small church of Saints Constantine and Helen (Agios Konstantinos and Agia Eleni) is located west of the village Avdou, on the boundaries with the dam of Aposelemis. It is a single aisled vaulted church with its interior adorned with frescoes by the brothers Emmanuel and Ioannis Fokas, very important representatives of the Constantinople art in Crete. The dedicatory inscription refers to the year 1445 and to the Byzantine emperor John VIII Palaeologus (1425-1448), although the Cretans had already experienced two centuries of Venetian occupation.
The dome of the apse is decorated with a representation of Christ Pantocrator, while below it we see the Hierarchs Basil and John Chrysostom. The main arch hosts the Hospitality of Abraham, flanked by the composition of the Annunciation (Virgin - Archangel Gabriel). The arch of the sanctuary is covered by the Ascension, Pentecost and the Presentation. In the vault of the nave we see some evangelical scenes (Candlemas, Descent into Hades, Crucifixion, Transfiguration, Healing of the Blind) and some scenes of Saint Constantine. The side walls depict Saints (full body). On the west wall we see the Dormition by Ioannis Fokas, and scenes from the Last Judgment. In front of the niche of the sanctuary, Saint Phanourios is represented as a deacon, just like the monastery of Agios Nikolaos in Zaros.