Rottenbuch Abbey was founded as an Augustinian monastery in 1073 on land granted by Duke Welf I of Bavaria. The Abbey church was constructed between 1085 and 1125 in the Romanesque style. The design of a crossing transept and free-standing tower is unusual for a Bavarian church. Rottenbuch was a center of papal loyalty during the Investiture Controversy. Under the patronage of Emperor Louis the Bavarian in the 14th century, together with its location on the pilgrimage route to Italy, Rottenbuch became the most influential house of Canons Regular in Germany.
In the 18th century the medieval interior of the church was redecorated in the ornate High Baroque style by painter Matthäus Günther and stuccoist Josef Schmuzer. With the secularization of the Bavarian monasteries under Montgelas in 1803 the monastic buildings were pulled down and the noteworthy library sent to a paper mill; the Abbey church became a parish church, which it remains to this day.
References:The Church of St Donatus name refers to Donatus of Zadar, who began construction on this church in the 9th century and ended it on the northeastern part of the Roman forum. It is the largest Pre-Romanesque building in Croatia.
The beginning of the building of the church was placed to the second half of the 8th century, and it is supposed to have been completed in the 9th century. The Zadar bishop and diplomat Donat (8th and 9th centuries) is credited with the building of the church. He led the representations of the Dalmatian cities to Constantinople and Charles the Great, which is why this church bears slight resemblance to Charlemagne's court chapels, especially the one in Aachen, and also to the Basilica of San Vitale in Ravenna. It belongs to the Pre-Romanesque architectural period.
The circular church, formerly domed, is 27 m high and is characterised by simplicity and technical primitivism.