Ratekau, north of Lübeck, is home to one of the best-preserved fieldstone churches in Ostholstein. In addition to the Romanesque nave from the 12th century, the building is characterised by a 48-metre-high round tower - formerly a defence tower. Erratic blocks, or fieldstones as they are also called in northern Germany, were used for the construction with the help of gypsum mortar from the Segeberger Kalkberg. Since the extensive renovation in 2012, concerts, readings and guided tours of the church have increasingly been held in addition to church services.