I saw old maps at the municipal museum.
This archive has many documents from the Edo period.
博物館 implies a large, comprehensive museum, while 資料館 is typically a smaller archive or local-history facility centered on documents.
Compound of 資料 (しりょう, 'materials, data') and 館 (かん, 'building, hall'). The term is a straightforward modern coinage for a facility housing reference materials.