Overgrown "Sühnekreuz". There was a page attached to them with a poem about the murder that happened there, later replaced by a shield, but eventually the latter was torn down.

The bridge leading to the location broke down last year, but you can still jump over the trench:

In a sidearm of a valley where I like to go hiking are some overgrown ruins; I wasn't able to find out who built these things and what they were - local history books do not mention them at all:

The Völklinger Hütte was a giant steelmill; dunno if it counts as abbandoned, as they keep it somewhat in use as a museum.

Bunker near the inner-German boarder. If the cold war would have become hot, the material stored in there would have been used to blow up civil infrastructure - especially bridges - in the region:

Military station near my home. It is said that ICBMs were stored here.

Graveyard of the communal psychiatry. Some nameless graves, some wardens. Four people died on a single day - it is unknown what happened back then.

A windmill that was part of the water supply. These were common - iirc - ~150 years ago. This is one of the few specimen that are still standing.
