memorial hall; museum (commemorating a person or event)
Typically a building or facility dedicated to preserving the memory of a notable person, historical event, or achievement. Often used in proper names like 〇〇記念館.
I plan to go to the Soseki Memorial Museum next week.
This memorial hall was built to pass on the memory of the war.
Compound of 記念 (commemoration, memory) and 館 (hall, building). The reading is standard on'yomi.