Sahagún is perhaps best known as the compiler of the "Historia general de las cosas de la Nueva España—"in English, "General History of the Things of New Spain—"(hereinafter referred to as "Historia General"). The most famous extant manuscript of the "Historia General" is the "Florentine Codex". It is a codex consisting of 2,400 pages organized into twelve books, with approximately 2,500 illustrations drawn by native artists using both native and European techniques. The alphabetic text is bilingual in Spanish and Nahuatl on opposing folios, and the pictorials should be considered a third kind of text. It documents the culture, religious cosmology (worldview), ritual practices, society, economics, and history of the Aztec people, and in Book 12 gives an account of the conquest of Mexico from the Tenochtitlan-Tlatelolco point of view. In the process of putting together the "Historia general", Sahagún pioneered new methods for gathering ethnographic information and validating its accuracy. The "Historia general" has been called "one of the most remarkable accounts of a non-Western culture ever composed," and Sahagún has been called the father of American ethnography. In 2015, his work was declared a World Heritage by the UNESCO.