Based on what your mom likes/didn't like, I can't pinpoint how she'd feel about Berlin but visiting the wall was a profound experience and I'm not even a big history buff. There's also a Holocaust museum there.
But it wasn't the prettiest city when I was there--which was a long time ago. There was a lot of construction. I'm still glad I went.
Yeah, she's very anti-not pretty. But if I can set it up so we do maybe a day trip filled with a museum, the major sites and a few nice restaurants , I can convince her.
I also did Vienna and Salzburg in Austria. Vienna was pretty grand with great architecture. I'm pretty sure they have good markets as well.
I did the Sound of Music Tour in Salzburg. Totally worth it. That area is gorgeous. I do recommend traveling by train in that area. You can just sit back and enjoy the scenery.
OMG I didn't know this was a thing, but my mom LOVES Sound of Music so I'm going to look into that and maybe leverage it with Berlin! :)