My brother-in-law told us about this location.
He is a native to the city this location is in, and when we met him, he contacted a friend to find out if it was still accessible.
We actually had another spot on our list, but that one was more of a nice-to-have, nothing spectacular, if at all accessible, it would be empty rooms - but secret-service-stuff, so actually kinda cool.
But the dairy company promised more of a photographic adventure, so we went for that option and drove there the next day.
The weather was perfect - an only partly cloudy sky, afternoon sun - made for some really cool shots.