Medieval fortifications on the East Frisian peninsula have been the focus of NIhK research for several years. The oldest house in Leer, the Harderwykenburg, has now been documented as the basis for an analysis of the building history. The building probably was built after the middle of the 15th century by the Leer chieftain Hajo Unken. It has been owned by the von Knyphausen family for around 200 years, who are committed to restoring and researching the property in accordance with monument regulations. The three-storey tower house is one of the best-preserved examples of this type of building in northern Germany. Despite some alterations around 1600 done by the clerk of Leerort Diederich Harderwyk, numerous medieval architectural details such as slit-shaped windows have been preserved.

Two drones were used to take high-resolution photos of the building from different perspectives to document the structural details. A 3D model was then calculated in a second step using the "structure-from-motion" method. This model forms the basis for a subsequent architectural history analysis. The new technology allows the creation of deformation-appropriate views of the walls, which previously could only be drawn on paper with a pencil using scaffolding.