In a small room on the south end of the porteria is the original mission baptistery. Here is the first baptismal font, which is a huge monolithic basin cut from gray volcanic stone. The outside is carved with both Christian and indigenous symbols. Carved medallions illustrate episodes in Christ’s life, and there is a relief of the Archangel Michael casting Lucifer from heaven. The indigenous symbolism includes Aztec speech markers and pre-Hispanic water imagery. Encircling the cord rim is a Spanish and Nahuatl inscription which says, “This baptismal font and the room in which it is found was mandated by the venerable guardian Fray Martin de Aguirre in the village of Zinacantepec in the year 1581.” This font is one of the most important pieces at the museum.