The Archcathedral Basilica of the Assumption of the Blessed Virgin Mary and Saint Andrew in Frombork was constructed during 1329-1388. The astronomer and mathematician Nicolaus Copernicus worked there as a canon (1512–16 and 1522–43). He wrote his epochal work, De revolutionibus orbium cœlestium in Frombork. Shortly after its 1543 publication, Copernicus died there and was buried in the cathedral where his grave was thought to have been found by archaeologists in 2005. This was subsequently confirmed in November 2008 by the publication of the results of DNA tests on fragments of bone and hair found on the skeleton; hair that matched two strands of hair which belonged to Copernicus and are currently located in Uppsala University.
In the northwest corner of the cathedral grounds is Copernicus' tower, and in the southwest corner an octagonal building with a square bell tower and a small planetarium and a Foucault's pendulum. Frombork suffered destruction during the Polish–Swedish wars. Between 1626 and 1635 it was occupied by Gustavus Adolphus of Swedenwho looted the cathedral and removed many cultural artefacts, including Copernicus' manuscripts to Sweden.
The town and cathedral were badly damaged in World War II. After the war the cathedral was meticulously reconstructed.
References:The first written record of church in Danmark locality date back to the year 1291. Close to the church are several stones with a Christian text and cross inscribed. The oldest parts of the present red-brick church are from the 1300s. In the late 1400s the church was enlarged to the appearance it has today. The church has been modified both internally and externally several times, among other things after the fires in 1699 and 1889. There are lot of well-preserved mural paintings in the walls.