The Trinity Church in Karlskrona is located south of the Grand Square in the city centre and was designed by Nicodemus. The Tessina Church is an octagonal central church with a dome, and the square features an impressive portico with four columns. The church belongs to the Karlskronska parish.
When Karlskrona was founded in 1680, it took a lot of work to build the town. In the first years of its existence, the Germans moved into the town. During the first decade they were allowed to conduct their own German-language services in the Hedwig Eleanor Church, a temporary wooden church built by the Swedish community of the town. In 1689 the Germans began to consider their own church premises and on 17 October of the same year they received permission from the king to form their own assembly according to the privileges he had granted the city. On 3 June 1697 the first stone was laid in the foundation of the church, but until 1709 the church was so ready that it could be consecrated that it happened on 27 June that year. However, it will take another 40 years before the construction is completed. Due to a large city fire in Karlskrona in 1790, the church burned down and only the walls remained after the fire. However, the church was rebuilt according to original drawings. The Trinity Church is also called German Church, as it was originally a church of a German assembly. The parish was founded in 1689 and existed until 1847, when it merged with the parish of Karlskrona. Together with Fredrikskirkan in Karlskrona, the Trinity Church is usually considered one of the main monuments of classical Roman baroque in Sweden. The church is part of the Karlskrona World Heritage Site, which was included in the UNESCO World Heritage List 1998.
When Nicodemus Tessinus di was commissioned to make drawings for the city church or Fredrikskircan and the German church or Trinity Church, he decided to make the latter in the form of a plan of the same type as Santa Maria dei Miracoli in Rome. The church was designed as an octagon with four transverse sleeves. Inside, the central church room was round. The southern transverse shoulder consisted of a cow and in the north was the main entrance. According to the surviving copies of the original drawing, the church had a large dome with round light apertures. The height of the dome was increased by a high octagonal lantern topped with a royal crown.
After a fire in 1790 only heavily damaged outer walls were left. In 1791 Olof Tempelmann was commissioned to prepare proposals for the reconstruction of the church, and Tempelmann's proposal shows a simplification of architectural details concerning the appearance of the church. These deviations from Tessin's drawings bring the building into balance with the neoclassical style of the time. The large Tessin dome and the lantern were replaced by a lower step dome and a low lantern with the Pantheon as a model, topped by a sphere with a cross. As for the portico of the main entrance, it took 1862 before it received its current design.
Twelve years after the re-consecration of the church in 1802, the interior of the church room was added. The sculptor Johan Törnström was in charge of this work.
In the altar section, located in the southern transverse sleeve, a neoclassical altar composition consisting of two columns with an openwork top with a sunbeam and a dove in the centre prevails. Below the clouds with the two winged heads of the angel. Originally, the altar included a large cross, which was removed during the reconstruction in 1912. The current gilded cross with a cloth and crown of thorns was originally made for Fredrikskircan according to the drawings of Johan Adolf Havermann in 1843. Due to the reconstruction in 1912, the altar window (which is now clogged and can only be seen from the outside) are decorative paintings with motifs from both churches of the Stortorget.
The Empire-style pulpit at the southeast wall of the church room is unusual in its design. It has a basket equipped with strong baluster dolls and is decorated with a sculptural curtain at the front. The sound ceiling is supported by two thin columns. There is also a sacristy in the pulpit. That Thurnstrom has found a model for this creation is unknown. Törnström was probably also responsible for the interior design of the bench. The interior of the bench is covered with rectangular mirrors. The decoration of the cassette of the large dome and the sunbeam of the lantern was also painted by Törnström.