You say stupid, but I actually would find it sad to see beautiful buildings that are in many cases hundreds of years old defaced with loads of small condensers bolted on to the face.
That doesn't mean they shouldn't have A/C but rather all flats use one system with a large roof condenser, or where that is not possible district cooling or ground source.
I'm not talking about historic buildings that are hundreds of years old. I live in Finland - we don't have many of these. Almost all apartments are built after the 60s outside the downtown and look like concrete boxes.
That doesn't mean they shouldn't have A/C but rather all flats use one system with a large roof condenser, or where that is not possible district cooling or ground source.