On the hiking trail, a trail sign shows the edge of the Wakld to the Urstein ruins. After the power pole, it goes into the forest and down to the Urstein castle ruins.
This is one of the 3 ruins of Herisau. Unfortunately you can only see a few stones there. The other 2 ruins of Herisau are much larger and better preserved.
The detour doesn't really bring much, not even in terms of scenery. The ruins can only be guessed at...
According to the map, there is a trail that leads down to the Urnäsch stream, but I don't know if it's worth it, and it looks rather steep and very difficult.