The church is built of red brick, indicating that it was constructed no earlier than 1170 when brick was first used in Denmark. Coincidentally, this is also the date of the site's first fortification, the nearby castle of
Esbern Snare (1127–1204). The architectural design, however, would indicate a rather later date, possibly in the first three decades of the 13th century. At the time when the church was built, a small medieval town stood on the hill. It was originally fortified by Snare's castle but this was replaced in the 14th century by
Kalundborg Friary, now in ruins, with its ring walls and ditches. Much of this has now disappeared but the old churchyard walls are still intact. Two brick houses from 1500 form part of the boundary walls and a few brick houses near the church are evidence of the prosperity the town enjoyed in the 15th century. The central tower of the church collapsed in 1827 due to structural flaws and incautious repairs inside the church. Collapse did not cause any injuries but many medieval furnishings were destroyed. As the church had fallen into a state of disrepair by the beginning of the 19th century, restoration work was carried out first from 1867 to 1871 under the leadership of architect
Vilhelm Tvede (1826–1891) when the central tower was rebuilt. Later from 1917 to 1921 the three entrances and the windows were reconstructed under architect Mogens Clemmensen (1885–1943) and his father
Andreas Clemmensen (1852–1928). From the square nave, four arms of equal length stretch out to a polygon terminal. These proportions have been compared to the description of the
New Jerusalem in the
Book of Revelation. While the original barrel vaults of the transepts are still in place, the columns in the nave and the vaults have been reconstructed. The medieval sacristy (1400) along the north wall of the chancel is well preserved. In about 1500 it was given an upper storey. ==Architecture==