The Library's rare book room includes an unusually rich and complete representation of English and first-generation Puritan works, including an original copy of the Cambridge Platform of 1649. The Library's archival collection of colonial-era church records is also extensive, containing many sets of seventeenth-century documents as well as full collections from large and historically significant modern churches like Boston's Old South Church and Park Street Church. Many of these records have been digitized and made accessible as part of the New England's Hidden Histories program.