[ExoticPearTree]

You can add AC systems in the attics and then run the piping inside the building. You keep the facade as it is.

I guess it depends on the country, customs and other things. In my part of Europe, older people are convinced the AC will kill them if they use it. So YMMV.

[spockz]

You can indeed. But then you lose significant space internally and not to mention the noise. Of course, better than having nothing. However, space in these houses comes at a premium as well.

[account42]

You don't need a lot of space for effective AC.