The remains of the Castle can be visited
Middle Wartenberg Castle (Ruin)

The Mittlerer Wartenberg ruin is on the highest point of the Wartenberg in Muttenz, in the canton of Basel-Landschaft, Switzerland. As part of an ensemble of three medieval castle complexes on this hill, it offers insight into regional history.
History+
The three Wartenberg castles formed a single unit until the end of the 13th century. Originally, the Strasbourg Cathedral Chapter was recorded as the owner of the Wartenberg castles and the village of Muttenz. It is believed that the Strasbourg archbishops leased the castles to the Counts of Homberg as early as the 11th century. After 1250, the castles were inhabited by the successors of the Hombergs, the Neu-Hombergs from the House of Frohburg, as well as by their liegemen, the Marschalk von Frohburg (later Marschalk von Wartenberg).
Source: Wikipedia · Licence: CC BY-SA 4.0
This description draws on the facts documented in the linked Wikipedia article; Wikipedia content is licensed under CC BY-SA 4.0. Wording and editing: Mobile History.
Location: 47.5189, 7.6548