Saint William's Church is a gothic church is known for its sumptuous interior combining the Gothic and Baroque styles. Since the end of the 19th century, the excellent acoustics of the church has allowed it to serve as a venue for concerts of classical music, in particular for the Passions of Johann Sebastian Bach.
Returning unharmed from the Crusades, the knight Henri de Müllenheim undertook the construction of a monastery for the Hermits of Saint William, an order of mendicant monks, in this marshy neighbourhood situated extra muros, that is, beyond the city walls. The elongated building, consecrated in 1301 and realised in 1307, is the only remnant of this group. Entirely brick and unvaulted, the church corresponds well to the ideal of the order, namely by its single nave and the simplicity of its exterior form. Sheltered by a pitched roof, its nave is topped and prolonged by a deep polygonal choir illuminated by high windows, which betrays its original function as the monks' meeting room. In 1331, by reason of its proximity to the port and wharfs, the church was chosen as parish by the newly established corporation of shipbuilders.
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.