I like the design on those side windows, but why are they bricked up? Is it something that was done to prevent intruders after the place was abandoned?

I like the design on those side windows, but why are they bricked up? Is it something that was done to prevent intruders after the place was abandoned?

I like the design on those side windows, but why are they bricked up?
The diamond ones.. It would be a lot of effort to brick them up with a design, maybe they were always like that?