Expand/extend an Art Nouveau villa

Hello everyone,
I have the following problem.
The building (built in 1899, 2 floors + attic and stucco facade) is to be extended. The question is... should the extension be done in the "old style" (certainly also very expensive) or should a completely new modern architecture, e.g. glass/steel, be chosen. The extension should be over the entire height, preferably with a roof terrace.
Are there any examples in this regard? Or what is done "these days".
Thanks for ideas or picture examples

Hello,

...The building (built 1899, 2 floors + attic and stucco facade) is to be expanded. The question is..

In my opinion, you should first get information from the local building authority during their consultation hours (opening times are posted, for larger building authorities relevant information can be found online) to find out if and what you are allowed to change at all. I would not be surprised if, due to the age of the building, you are not allowed to remodel/add just anything according to your taste.

Kind regards

Thank you for the information. I have already been to the building authority with my standard architect. However, I have mostly done utility buildings and functional solutions in multi-family houses with the architect so far. Therefore, I am still looking for ideas. The building authority has largely given me the green light. Of course, not an entire additional floor or anything like that. But for the extension, I have the green light.