The public buildings in the town were designed by Erik Dahlberg (1625-1703) and Nicodemus Tessin the elder (1615–81), and also his son, Nicodemus Tessin the younger (1654–1728).

The planners of Karlskrona intended that the churches should play a prominent part in the life of the town. As with the temples of Greece and Rome they were situated on a spacious open Square and as church attendance was mandatory, the buildings had to be big enough to accommodate large congregations. The King, Karl XI, enjoyed absolute power during this period and placed considerable weight on the importance of religion. It is said that he had once remarked “True fear of the Lord is one of the most noble, indispensable and beneficial things in Our Armed Forces.”

The first parish church in the town, the wooden Hedvig Eleonora church was on Drottninggatan. The former churchyard is now a small park.

The Fredrik Church. Originally called the Swedish, or the Great Church, the Fredrik Church was the town parish church. This cruciform building designed in the 1690’s resembles a Roman basilica and was the largest of the churches built by Tessin the younger. The facade was probably inspired by the Santa Trinita dei Monti church at the top of the Spanish Steps in Rome. Construction work began in 1720, and after consecration in 1744 it replaced the Hedvig Eleonora church. The church was named after King Fredrik I (1676–1751).

The Church of the Holy Trinity. There was a considerable number of German citizens amongst those who had moved to the new town of Karlskrona and they were granted permission to build their own church. The rotunda, inspired by Italian architecture, became known as the German church and was built by Nicodemus Tessin the younger. Work on the building was begun in 1697 and the church was consecrated in 1709 before it had been completed. After the fire of 1790 no more than the badly damaged walls remained and the church was later rebuilt after Tessin’s plans.

The Admiralty Church. The site of the Admiralty church “Ulrica Pia” had already been laid down in the town plan from 1683 and the drawings for the building, designed to hold a congregation of some 4,000, have probably been drawn up by Erik Dahlberg. The ground plan is in the form of a Greek cross. Consecrated in 1685, although the interior was not completed until several decades later, it was named after Karl XI’s Queen, Ulrica Eleonora. The well-known statue of “old Rosenbom”, a sailor from the eighteenth century holding the poor box, stands outside the main door of the church.