Aztec culture and history is primarily known through archaeological evidence found in excavations such as that of the renowned Templo Mayor in Mexico City; from indigenous bark paper codices ; from eyewitness accounts by Spanish conquistadors such as Hernán Cortés and Bernal Díaz del Castillo ; and especially from 16th and 17th century descriptions of Aztec culture and history written by Spanish clergymen and literate Aztecs in the Spanish or Nahuatl language, such as the famous Florentine Codex compiled by the Franciscan monk Bernardino de Sahagún with the help of indigenous Aztec informants.