Frankenberg Castle was constructed during the 13th century and historically it was the seat of a Vogt, local administrator. Until the end of the 19th century, the castle consisted of a broad forecastle, a farmyard, and a main castle (which was completely surrounded by water).
With the introduction of the French Constitution of 1793, Frankenberg Castle lost its status as a fief of Jülich. Between 1834 and 1838, the property underwent comprehensive renovation and modernization.
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.