Sepia Photograph, 7.25" x 4.5". Plaque on base supporting the stone reads in part (in translation): "Aztec Calendar or Sun Stone. In the month of December in the year of 1790, while leveling the ground for a new pavement in the Plaza Mayor of the capital city, this monolith was discovered and set at the foot of the western tower of the [National] Cathedral ... it was moved from this location to this Museo Nacional in August of 1885."