Vaasa Church was planned by the architect C. A. Setterberg and consecrated in 1869. The church, built in an English neo-gothic style, has a capacity of almost 900 people. The last restoration took place in the year 2000.
The church has three altarpieces: The Institution of the Eucharist by R. W. Ekman (1861), The Adoration of the Angels by Albert Edelfelt (1894), and The Deposition of Christ by Louis Sparre (1897).
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.