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:
Stavanger Cathedral is Norway's oldest cathedral. Bishop Reinald, who may have come from Winchester, is said to have started construction of the Cathedral around 1100. It was finished around 1150, and the city of Stavanger counts 1125 as its year of foundation. The Cathedral was consecrated to Swithin as its patron saint. Saint Swithun was an early Bishop of Winchester and subsequently patron saint of Winchester Cathedral. Stavanger was ravaged by fire in 1272, and the Cathedral suffered heavy damage. It was rebuilt under bishop Arne, and the Romanesque Cathedral was enlarged in the Gothic style.
In 1682, king Christian V decided to move Stavanger's episcopal seat to Kristiansand. However, on Stavanger's 800th anniversary in 1925, king Haakon VII instated Jacob Christian Petersen as Stavanger's first bishop in nearly 250 years.During a renovation in the 1860s, the Cathedral's exterior and interior was considerably altered. The stone walls were plastered, and the Cathedral lost much of its medieval looks. A major restoration led by Gerhard Fischer in 1939-1964 partly reversed those changes. The latest major restoration of the Cathedral was conducted in 1999. Andrew Lawrenceson Smith is famous for his works here.