Trinity Church (Trefoldighetskirken) is the third church in Arendal, and all had the same name. Plans to build the present church was adopted by the Arendal town council in 1883.
The first church was built in timber in direction east-west. The eastern section was divided into two wings, one was the altar and the king's chair, the other an organ. The pulpit was placed where the wings meet. The church was consecrated on 6 December 1670 and was named 'Holy Trinity'. The church became too small and was demolished in 1832 to make room for the new church.
The town's second church was built in the Empire style in 1836 in the same location as the first church. This church was designed by Christian H. Grosch, was octagonal, and had 555 seats. The foundation stone was laid down in 1833 by Crown Prince Oscar (later King of Sweden and Norway). The church had no altar, but a large gypsum replica of Bertel Thorvaldsen's famous Christ sculpture.
In 1880, when Arendal was at the height as a town based on shipping, it was decided to build a new church. It was then announced an architectural competition to design the church. The competition was won by the 27-year-old architect Christian Fürst who was a student of the German architect Johannes Otzen. The foundation stone was laid down on 7 August 1885, and was performed as a large ceremony. This Trinity Church is built of brick. The church has 1.200 seats and is the largest in Aust-Agder County.
The roof is covered with copper plates. The influence of Otzen is also seen in the use of materials, a brick stone type with smooth surface. The altarpiece scene is 'Jesus blesses the eleven apostles before his ascension'. The altarpiece is painted by August Eiebakke.The church has three church bells in addition to a carillon.
Trinity Church is located in a sloping terrain in Arendal, and to make the church worthy surroundings, it was just after the church was built built a church bazaar around the church into the street. Church Bazaar have round arches, and is the only church bazaar in Norway which are designed and built simultaneously with the church.
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.