On the castle ring near Schwalefeld are the remains of a ring fortress from the early Middle Ages. The Schwalenburg fortification consists of three rampart rings and ditches, encloses an area of six hectares and is therefore one of the most impressive early historical fortifications in Central Europe.
The oldest part of the complex is the middle ring, which encloses an area of two hectares. It has an almost oval shape and appears today as a mighty rampart with a ditch in front of it. In the north-east of this ring there was a mighty gate, still clearly recognizable by the inward bending rampart ends. A smaller gate, which was added later, is located in the south of the middle ring.
The inner, almost circular rampart ring has a diameter of 75 to 90 meters. In the north, it has an approx. 2.40 m wide gate lane, the remains of the walls of which can still be seen, and a steep-sided pit, which could be a well or the cellar of a tower. Remains of walls can be found in the inner ring, suggesting that there were rooms of different sizes attached to the rampart.
The outer ring of ramparts encloses an area of six hectares. It was the mightiest of the three Wallen and had a ditch in front of it. The two-metre wide, timber-reinforced wall with an internal ramp was around 5 metres high.
At the beginning of the 20th century, excavations were carried out at Schwalenburg Castle, but nothing is known about the contents of the excavations, apart from the ruined wall fronts visible today. All documents and the recovered finds have been lost. However, the traces of lime mortar in the gate of the inner ring and also on the gate of the middle ring, which was built in later, show that the complex must belong to the early Middle Ages (8th to 10th century). In 1537, the "Borgh zu Schwalefeld" is mentioned for the first time in the land register and even then as being overgrown with wood.
The Diemelsee Nature Park makes a special effort to preserve architectural monuments from past centuries. The "Schwalenburg" has been cleared of vegetation and a small observation tower provides visitors with an overview of the mighty fortifications from the Carolingian period. Eight information boards along the "Schwalenburg Ringwall Trail", which was newly created in 2015, give visitors an understanding of the castle's history. An accompanying flyer has been published.