archival (adj.)

c. 1600, "records or documents preserved as evidence," from French archif (16c., Modern French archives), from Late Latin archivum (plural archiva) "written records," also the place where they are kept, from Greek ta arkheia "public records," plural of arkheion "town hall, public building," from arkhē "government," literally "beginning, origin, first place" (verbal noun of arkhein "to be the first;" see archon). The sense of "place where public records and historical documents are kept" in English is from 1640s.

suffix forming adjectives from nouns or other adjectives, "of, like, related to, pertaining to," Middle English -al, -el, from French or directly from Latin -alis (see -al (2)).