The ruins of Frohberg castle is on a rocky ridge at the upper end of the Klus valley on the way to the old Platten pass road. The stronghold at Frohberg was first mentioned in 1292 when Conrad I Schaler 'de Vroberg' was mentioned. It is likely that the castle was built by the Schaler family in the second half of the 13th Century. Although the castle dominated the way across the Platten pass (between Birseck and Laufental), the location of other castles in the immediate vicinity, suggests that the motivation for the castle was not the collection of tolls, but power games between the families of the Schaler and Münch.
The castle was perhaps never quite finished or it castle was damaged during the Basel earthquake of 1356 and was not repaired. In any case, in the 14th Century, the remains were given as a bishop's fief to the counts of Thierstein-Pfeffingen. This fief was not so much about the ruins, which needed costly repairs, but the assets related to the castle including tax collection and court rights.
The ruins are widely scattered and consists of an extended main castle, surrounded by different approach obstacles. So far, the ruins have not yet been investigated archaeologically and so only rough interpretations are possible. The main castle was formed by a housing tract and a curtain wall. The wall follows the irregularly extending ledge. The massive living area consists of two parts and a smaller west building with irregular floor plan as a residential tower. The thick walls were up to 3 meters thick and built from rough cut stone. To the east, adjoining the living area, is an elongated building that served as an administrative and residential building. On the northwest and northeast sides the remains of outlying estates are visible.References:
Augustusburg Palace represents one of the first examples of Rococo creations in Germany. For the Cologne elector and archbishop Clemens August of the House of Wittelsbach it was the favourite residence. In 1725 the Westphalian architect Johann Conrad Schlaun was commissioned by Clemens August to begin the construction of the palace on the ruins of a medieval moated castle.
In 1728, the Bavarian court architect François de Cuvilliés took over and made the palace into one of the most glorious residences of its time. Until its completion in 1768, numerous outstanding artists of European renown contributed to its beauty. A prime example of the calibre of artists employed here is Balthasar Neumann, who created the design for the magnificent staircase, an enchanting creation full of dynamism and elegance. The magical interplay of architecture, sculpture, painting and garden design made the Brühl Palaces a masterpiece of German Rococo.
UNESCO honoured history and present of the Rococo Palaces by inscribing Augustusburg Palace – together with Falkenlust Palace and their extensive gardens – on the World Heritage List in 1984. From 1949 onwards, Augustusburg Palace was used for representative purposes by the German Federal President and the Federal Government for many decades.
In 1728, Dominique Girard designed the palace gardens according to French models. Owing to constant renovation and care, it is today one of the most authentic examples of 18th century garden design in Europe. Next to the Baroque gardens, Peter Joseph Lenné redesigned the forested areas based on English landscaping models. Today it is a wonderful place to have a walk.