Breakdown of kannai wa shizuka desu.
Questions & Answers about kannai wa shizuka desu.
は marks the topic of the sentence.
So 館内は means something like:
- as for the inside of the building/facility
- inside the building, ...
The rest of the sentence, 静かです, says something about that topic.
So the structure is:
- 館内は = topic
- 静かです = comment about the topic
This topic-comment structure is extremely common in Japanese.
