noun, noun, used as a suffix
building; hall; public building
Used as a suffix to name a large building or hall, often for a specific purpose (e.g., 図書館, 博物館). As a standalone noun, it refers to a large or public building.
この町には立派な図書館がある。
There is a fine library in this town.
あの大きな館は何ですか。
What is that large building?
建物 is a general term for any building, while 館 specifically refers to a large, often public or named building.
The kanji 館 is composed of 食 (eat) and 官 (official), originally meaning a place where officials were fed, later extended to mean a large building or hall.