The frescoes date from the Gründerzeit period around 1215.The “Bestiarium," the representation of demonic powers and mythical creatures in the base area, is quite famous. Christ with the four symbols of the evangelists, surrounded by the twelve apostles arranged in pairs, is in the middle of the apse. On the left and on the right, an atlas supports the sky and in between hermaphrodites, half human, half animal; and above them are Cain and Abel, who offer their sacrifices.
St. Jakob's Church in Kastelaz is open daily from spring to autumn; guided tours for groups are available on request or as part of the weekly village tour.
The special feature of the Romanesque frescoes in St. Jakob's Church in Kastelaz is the imaginatively detailed bestiary, the representation of demonic powers and dangerous mythical creatures of the ancient mythology, which are pictured at the pedestal. They too reach up to the apostles and thus illustrate the break, but also the transcendence between the holy and the demons. It is about a representation of the cosmos, the divine above, the unholy below. The hybrids thus symbolise the antithesis of the divine order.