Codex Vergara is an Aztec cadastral document, drawn up in 1539 by the Spanish conquerors of Mexico, on behalf of the king of Spain, in order to facilitate the collection of taxes from the native population. The document records the landholdings of the Aztec villages of Calcantloxiuco, Topotitlan, Patlachiuca, Teocatitla, and Texcalticpac. These villages and their locations and sizes are represented on the document. The first seven pages show the genealogy of the families of landowners and their connections to the various plots of land. In the upper-left corner of the page, the chantli (family home) is shown, followed by a human head without a body that represents the head of the household, which is connected to other family members by a horizontal line. Above the head, a phonetic symbol indicates the person’s name. The actual cadastral document starts on the sixth folio. Plots of land are represented as groups of four or five dominos stacked on top of each other. The codex is one of the two most significant census and cadastral surveys of an ancient state in the Americas (the other is the Códice de Santa María Asunción). It records the surface areas of fields as well as perimeter measurements with a mathematical accuracy that compares well with Western surveys made several centuries later. This document is crucial to our understanding of colonial Mexico. It includes, along with other information, approximately 500 family names. The codex is written in pictograms and in the Nahuatl language on European paper, imported by the Spanish into Mexico.