Zwiefalten Abbey was a Benedictine monastery founded in 1089 at the time of the Investiture Controversy by Counts Gero and Kuno of Achalm, advised by Bishop Adalbero of Würzburg and Abbot William of Hirsau. The first monks were also from Hirsau Abbey, home of the Hirsau Reforms (under the influence of the Cluniac reforms), which strongly influenced the new foundation. Noker von Zwiefalten was the first abbot and led from 1065–90.
During the 12th century Saint Ernest (died 1148) was abbot. Between 1145 and 1149 he participated in the Second Crusade to regain the Holy Lands including Jerusalem.
Although Pope Urban VI granted special privileges to it, Zwiefalten Abbey was nevertheless the private monastery of the Counts of Achalm, later succeeded by the Counts of Württemberg. The abbey was plundered in 1525 during the German Peasants' War. Christoph Rassler was abbot from 1658–75 and Augustin Stegmüller was abbot in the 18th century.
In 1750 the abbey was granted the status of Reichsabtei, which meant that it had the status of an independent power subject only to the Imperial Crown and was free of the rule of Württemberg. On 25 November 1802, however, it was secularised and dissolved and became a lunatic asylum and later psychiatric hospital, which it is today, as well as the site of the Württemberg Psychiatry Museum.
The present buildings were constructed in German Baroque style from 1739–47 under the direction of Johann Michael Fischer (1692–1766) of Munich, who began overseeing the work in 1741. The interior, considered a model of Baroque design, is filled with ornate chapels and gilded balustrades, dominated by the high altar, which combines a Gothic statue of the Virgin Mary dating from 1430 with Baroque additions (dating from about 1750) by Johann Joseph Christian (1706–77). The elaborate frescoes are by Franz Joseph Spiegler (1691–1757).
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.