The castle complex on the Willibaldsberg was begun in 1355 and extended in the second half of the 16th century under Martin von Schaumberg. It was transformed into an impressive residence by Elias Holl during the reign of Prince-Bishop Johann Conrad von Gemmingen (1595-1612) – at this stage of the building's history the towers were crowned by onion domes.
Gemmingen also laid out the renowned botanical garden Hortus Eystettensis. Based on the copperplate engravings illustrating the plant collection which were created in 1613 by Basilius Besler, the Bastion Garden opened in 1998 reproduces the plant world of the original botanical garden.
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.