The most complete surviving account of Aztec civilization at the moment of the Spanish conquest — a bilingual Nahuatl/Spanish encyclopedia compiled by a Franciscan friar working with Nahua scholars and artists over three decades. Twelve books cover the gods, ceremonies, divination, rhetoric, kingship, trade, natural history, and the conquest itself, illustrated throughout by Indigenous tlacuiloque. All twelve volumes, complete, in real facsimile from the Library of Congress copy — 2,439 pages.
Between roughly 1545 and 1590, the Franciscan friar Bernardino de Sahagun worked with Nahua scholars, scribes, and artists in Mexico City to compile the most complete surviving record of Aztec civilization on the eve of its destruction by Spanish conquest -- twelve books covering the gods, ceremonies, divination, rhetoric, kingship, trade, natural history, and finally the conquest itself, all illustrated by Indigenous tlacuiloque and written in parallel columns of Nahuatl and Spanish. It's a genuinely strange document: part ethnography, part propaganda, produced by colonizers and colonized working side by side under circumstances neither side controlled, and it remains the single richest primary source historians have for how the Aztec world understood itself just before that understanding was violently overwritten.