I did not think about an tax issue.
Here I find it typical that unused industrial buildings etc. remain left to themselves for a decades. Being by that time damaged to their structure. Then when they are going to be demolished some people realize their former architectural value and in vain try to stop the demolition. Or someone gets the idea that they would be ideal for housing, office, retail etc. and restores or rather rebuilds them…
Back to photography. In Wolfen they kept one building out of the first building phase alive to remind of the history of that place incorporating a museum.