The church was founded back in c. 800 in the time of Charlemagne. It originally belonged to the Convent of St John in Müstair. The simple construction with a square ground-plan conceals extremely rare interior decoration. The altar niches in the east wall are most impressive, terminating in horseshoe arches. In the central niche Christ is flanked by two angels; Pope Gregory the Great and St Stephen can be seen in the two side niches. This portrayal of the two founder figures with square haloes is unique. The clerical founder is holding a model of the church in one hand whilst the secular lord is holding the sword as a symbol of power. This is the only representation in Europe of a Frankish secular lord in traditional garb. Fragments of frescoes on the north wall indicate that the wall was once decorated in its entirety. Scenes from the Conversion of Saul and the Life of St Benedict can be recognized. Under Joseph II this treasure was desecrated and, until its rediscovery in the 20th century, the church was used as a storeroom.