The Church of St Donatus in Zadar is located in the center of the historical core of the city, on the ruins of what used to be an ancient Roman forum.
It was dedicated to the Holy Trinity, but it was renamed in the 15th century and today carries the name of St Donatus, the bishop who, legend has it, commissioned its construction probably in early 9th century. The church was first mentioned in the text De Administrando Imperio (On the Governance of the Empire), compiled and written by the Byzantine emperor Constantine VII Porphyrogennetos aroung 950 A.D. It was constructed on the basis of early Byzantine architectural traditions of the Early Middle Ages. It is round in shape, with a double ring which can also be found on several other European buildings dating from that period, among which it stands out due to its originality.

The church was not preserved in its original form. Its southern annex was brought down in 1930 so today we can see its central circular core. The church is a part of episcopal complex and leans to an Early Christian cathedral and the Bishop’s palace. It is Cylindrical in shape, with three high apses annexed on the eastern side. Below the roof on the southern side are three openings which used to lead from the gallery to the southern annex. It was used a place of worship until 1798.

The foundations of the church have been bared, revealing in-built antique material – fragments of ancient pillars, stone beams, capitals and other various arhitectural elements. Most important of the numerous fragments built into its foundations are the remains of the sacrificial altar and the base of a deity statue with an inscription dedicated to the goddess Juno and the supreme deity, Jupiter. The entrance portal is also composed of ancient stone beams (architraves), like the portal of the gallery. The original floor has been removed and now reveals the panels of the ancient forum.

Widely-known music nights have been held in this exceptionally acoustic space for the last fifity years, promoting the early music of masters of music from both Croatia and the rest of the world.