Let alone/Not to mention/much less

I've never been to China, let alone see the Great Wall.

I've never been to China, not mention see the Great Wall.

I've never been to China, much less see the Great Wall.

文章イメージ：前節に大きな話、後節に小さな話

The Great Wall of China is a big tourist attraction and historical feature.

feature

 noun/ˈfiːtʃə(r)/ˈfiːtʃər/[countable] something important, interesting or typical of a place or thing

What's the expression that we can substitute in this situation? We could say... 

There are some exceptions.

I'm aware of this expression all the time around me.

7 days trekking with my son was really nice, not to mention mountain views.

not to mention　肯定文でも使える