The museum is currently the custodian of the town’s charters and corporation records. Of the 120 charters and associated documents, 81 date from before 1500. The earliest datable document is the charter of Henry De Lacy, Baron of Halton and later Earl of Lincoln, written in 1272, however this document is not part of the collection currently. This allowed the men of Congleton the right to hold land through the payment of a money rent rather than by personal service to the Lord of the Manor. It also gave the inhabitants of the town the right to elect a Mayor.
Initially legal documents, these charters are also works of art. The most decorative is the 1625 charter of James I.