We started walking up the Brotjacklriegel mountain in the previous post. In this post a few more rocks, a stone (not the same thing as a rock), and a tower.
The tower is on top of the mountain for the same reasons other towers are on top of a mountain: humans who want to leave a graffiti saying "We were here" and being able to look over the trees covering that top.
The stone (Du-Stein) was the idea of a climber who had found out that above a certain altitude people started calling each other Du (you) and not Sie (you, but politely - English doesn't even have it). He decided that altitude was a 1000 metres, so that's where the stone is standing now.