The Niederburg ruins ('Lower Castle') at Kobern stand at a height of about 150 metres above the village of Kobern on a hill ridge that points towards the Moselle. On the same ridge and about 50 metres higher, is the Oberburg ('Upper Castle') and St. Matthias' Chapel.
The castle has an amygdaloidal ground plan. It has a three-storey, 20-metre-high bergfried, measuring 7.5 x 8 metres, with an elevated entrance at a height of 10 metres. There are also the remains of a two-storey, Late Gothic palas. A wall tower and a cistern are also well preserved and there are significant portions of the outer walls. The castle was guarded to the west by a curtain wall with a zwinger and to the north by a throat ditch. The upper third of the bergfried and the battlements were rebuilt in the 19th century. Between 1976 and 1978, the state castle administration reconstructed and enhanced the palas and the cistern between the two towers.
The castle was built in the mid-12th century. It is first recorded in 1195, when the then Burgherr made it a fiefdom of the Electorate of Trier. The female line of the lords of Isenburg-Kobern died out in the 13th century. The Kobern Castles and associated lordship passed via the heiress, Cecilia, to Frederick II of Neuerburg (a side line of the counts of Vianden). In 1309 the male line of this family also died out. Thereafter the castle and lordship was sold to the Archbishop of Trier. In 1688 the castle was destroyed.
The castle is open to the public all year round and may be visited free of charge. Visitors may climb up to the castle on a footpath from the Mühlbach valley.
References:Ehrenbreitstein Fortress was built as the backbone of the regional fortification system, Festung Koblenz, by Prussia between 1817 and 1832 and guarded the middle Rhine region, an area that had been invaded by French troops repeatedly before. The fortress was never attacked.
Early fortifications at the site can be dated back to about 1000 BC. At about AD 1000 Ehrenbert erected a castle. The Archbishops of Trier expanded it with a supporting castle Burg Helferstein and guarded the Holy Tunic in it from 1657 to 1794. Successive Archbishops used the castle's strategic importance to barter between contending powers; thus in 1672 at the outset of war between France and Germany the Archbishop refused requests both from the envoys of Louis XIV and from Brandenburg's Ambassador, Christoph Caspar von Blumenthal, to permit the passage of troops across the Rhine.