Niasvizh Catholic Corpus Christi church was built in 1587–1593 according to the design of the Italian architect Giovanni Maria Bernardoni at sponsorship of Mikołaj Krzysztof Radziwiłł. The Jesuit church in Niasvizh was the first construction in Baroque in the whole territory of Rzecz Pospolita.
The temple interior is richly decorated with paintings. The frescoes were performed in 1750-1760s with participation of the artist Ksawery Dominik Heski (restored in 1900–1902). The frescoes embrace 40 individual compositions depicting Saints, allegorical scenes and biblical stories. The fresco compositions include cartouches with the Bible stanze and references. There is K.D. Gesski’s picture 'The Lord's Supper' (1753) in the main shrine. In addition to the paintings, the church interior contains a lot of plastic images, i.e. bás-reliefs and bust gravestones of the 17th – 19th centuries, marble altars and monuments.
There is a choir with an organ above the temple entrance. An entrance into the family crypt – a burial vault of the Radziwills – is located next to the bás-relief under the altar of Christ. There are over seventy burials of the mighty dynasty in the semi-basement.
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.