In the 12th century, a small stone church was built at Lunnertoppen. The location was the site an ancient settlement, as evidenced by the burial mounds around the church. The church itself had two remarkable features: a round stone tower facing west and a number of unique stone figures. According to the Norwegian Directorate for Cultural Heritage, the Lunner tower is the only round stone tower from the Middle Ages found in Norway. The tower was demolished in the 1780s when a timber extension was built, but the foundation for the tower can still be seen through a glass floor inside the church.
The entrance to the church was through a rounded portal on the far west side of the southern wall. Inside, the top of the portal features a three-leaf carving in soapstone. The style in the oldest part of the church is Romanesque. Further east on the southern wall is the priest's door, which has a pointed portal. The shape of the priest's door and the window in the eastern wall reveal that this section of the church has a Gothic style. The third entrance to the church was through the tower, but this disappeared when the tower was demolished. The passage into the church can been seen through the glass floor.
Fortunately, the unique stone figures have been preserved and are now located on the exterior wall of the vestry and on the southern and eastern walls of the stone church. The quantity and quality of the figures are very unusual for a country church.