The Presidential Palace in Vietnam is a historically-culturally significant place.
Is the sentence acceptable? Thanks a lot.

No: The compound adverb "historically-culturally" is wrong. And "significant" would be better placed at the beginning of the noun phrase:

"The Presidential Palace in Vietnam is a significant historically cultural place".


PaulM

I'd like to rewrite the sentence in the OP like this:
The Presidential Palace in Vietnam is a historically and culturally significant place.
Please check it. Thanks again.

Yes, that is possible.




PaulM