Buried within the Las Pinturas pyramid in San Bartolo, Guatemala, thousands of painted plaster mural fragments offer a window into ancient Maya civilization. Two of those fragments form the earliest known record of a Maya calendar, created between 300 and 200 B.C. The fragments depict the date of “7 Deer” from the 260-day sacred calendar common across ancient Mesoamerica and still used today by indigenous communities in Guatemala and southern Mexico.