The original castle on the Marienberg, a hill which was first settled in the late Bronze Age, was probably a small fort built early in the 8th century by the Franconian-Thuringian dukes, together with a church which in 741 became the first church of the Würzburg bishops. From 1200 an unusually large castle was built, which was extended during the late Middle Ages and the Renaissance.
Following the storming of the castle in 1631 by the Swedes, Prince-Bishop Johann Philipp von Schönborn built a circle of massive bastions to protect the Marienberg. In 1945 the fortress was almost completely burned out, and its reconstruction was only completed in 1990.
On the first floor of the Princes' Building Museum (administered by the Bavarian Palace Department), is the Bibra Apartment with valuable furniture, tapestries and paintings, the Princes' Hall with early Gothic arcatures and the large Echtersche family tapestry, as well as a treasury and vestment chamber from the era of the prince-bishops. On the second floor is the Main-Franconian Museum documenting the history of the fortress and town.
The 1,300 m2 Princes' Garden is accessible from the castle courtyard: it was reconstructed in 1937-38 on the basis of plans dating from the early 18th century.
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.