The immediately adjacent castle Ruchenstein was demolished in 1643, when the small fort was rebuilt into a Schloss Kasteln.

Because the builder had no previous expertise, and the client was mostly absent, the conversion proved to be expensive and lasted until 1650.

[1] It was the smallest bailiwick of the Bernese Aargau, consisting of the villages Auenstein, Oberflachs, Schinznach (now Schinznach-Bad and Schinznach-Dorf) and Villnachern.

After the fall of the Ancien Régime and the Act of Mediation in 1803, the bailiwick came into possession of the newly formed canton of Aargau.

In 1855 the brothers Frederick and Louis Carnival of Aarau acquired the property and opened a "rescue institution for orphans and neglected pupils" of the Reformed denomination.

The Institute received the status of a foundation in 1923 and was converted in 1955 in a boarding school for students with behavioral problems.