Tricarico Cathedral is a Roman Catholic cathedral church in the city of Tricarico. Robert Guiscard erected the present building in the Romanesque style in the 11th century using a gift from his nephew Robert, Count of Montescaglioso. Louis I, Duke of Anjou was crowned there in 1383. The church has been remodelled and enlarged several times over the centuries, by Bishops Pier Luigi Carafa senior in 1638, Pier Luigi Carafa junior after the plague of 1657 and Antonio del Plato between 1774 and 1777. The work carried out by the latter bishop gave the cathedral its present appearance.
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.