Fredrikskyrkan is the Swedish national church of Karlskrona, one of the two baroque churches that flank Stortorget. Designed by Nicodemus Tessin the Younger, architect of the Royal Palace in Stockholm, and consecrated in 1744, it is a large, austere building with a grand interior fitted out in the understated Swedish baroque style. The church is named for King Frederick I and serves as the main church for the city.
The round portico and the twin towers above the square give the church its characteristic silhouette. The interior is well preserved and contains several pieces of maritime art reflecting the city's naval history. Entry is free and the church is generally open to visitors during the day. Together with Trefaldighetskyrkan across the square, it forms one of the most harmonious baroque urban compositions in Scandinavia.