Only 2 sentences ---- Do these sentences share the same meaning?

The first isn't precise and doesn't tell you that the architecture is the reason for the designation. It's not clear that Gammelstad itself is actually the WHS (Gammelstad could be inside a larger area that has been so designated, for example).

Sentence two is more correct. I always dislike "because" and try to get the word out of the way at the beginning of the sentence. For this reason, although sentence two is more correct, I find it clumsy. To me:" Because of its preservation...(comma after architecture) then complete the rest of the sentence. I know you didn't ask all this but hope it adds insight now or later.

Yes, both sentences have the same meaning to describe a UNESCO site. They both describe the architecture of a museum constructed to hold artifacts for the Holocaust. Good luck.

Different emphasis.