Ringwall der Marienburg bei Nordstemmen, Medieval hillfort in Schulenburg, Germany.

The Ringwall der Marienburg is an earthen rampart about 700 metres long that encloses almost the entire summit of the Marienberg, covering 6.22 hectares. The wall still reaches 6 metres in height and 10 to 15 metres in width in places, with a ditch in front at vulnerable sections. Schloss Marienburg, built between 1857 and 1867, was constructed inside the ringwall.

No archaeological excavation of the wall has been carried out, so its construction and date remain unconfirmed. It is often dated to the Iron Age, but comparison with similar earthworks near the Marienberg, such as the Isenburg and the Düsselburg, points to the 8th to 12th centuries. Such defences were probably used only sporadically, as refuges for the population and their livestock in times of danger.

The fortification served as a defensive center and gathering place for the local population across medieval times. The earthwork remains a visible landmark in the landscape, reflecting how earlier inhabitants shaped their surroundings.

The site sits on a hilltop and is accessible on foot, with the climb to the summit taking around 15 to 20 minutes. Some sections of the walls are steep and muddy areas can be slippery, particularly after rain.

The spring fed by a gap in the eastern rampart drains outward into the Sachsenhain. The rampart itself was built as a timber-and-earth construction, with wooden inserts giving the earthen body stability. No targeted archaeological excavation has ever taken place, so its layout and date remain unconfirmed.