The earliest known document of Onsenoort Castle dates from 1286. The first castle was badly damaged and restored before 1372 in the border wars between local landlords. After it was changed hands several times the castle was again destroyed by French army in 1787. Today on the keep remains of a medieval castle. Current buildings were mainly built or restored in the late 1800s and early 1900s.
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.