Piedra del Sol (1250/1500) by unknownMuseo Nacional de Antropología, México
In December 1790, workers in Mexico City were excavating land to build the Plaza Mayor when they came across an enormous boulder. As the soil was brushed away, the intricate carvings revealed that this was an ancient Aztec monolith, buried by the Christian conquistadors.
The Mexican anthropologist Antonio de León y Gama visited the site and quickly determined that it was some kind of calendar. At first, the church authorities wanted to rebury this pagan object, but León y Gama argued successfully that it was of historic and artistic importance.
In July 1791, the stone was placed on exhibition on the western side of the Metropolitan Cathedral. It proved to be a major tourist attraction, and was recognised by many as an artistic triumph. It is currently held in the National Anthropology Museum, Mexico City.
What does it mean?
The Sun Stone, or Piedra del Sol, is a representation of the Aztec concept of time, its cyclical nature, and the relationship between the gods and humans. In one sense it's a calendar, but it's ceremonial rather than practical.
If you're used to using the Gregorian Calendar (as most of the world is) the Aztec calendar appears to be very complicated. This is because they used separate, but connected calendars to mark earthly time and ritual time.
The Aztec solar year lasted 365 days. There were 18 months of 20 days, as well as 5 intercalary days. They also used a 13-month, 260-day ritual calendar. Every 52 years, or 18980 days, the ritual and solar calendars coincided. This is sometimes called an 'Aztec century'.
While the calendar was central to Aztec beliefs, it wasn't entirely their own invention. The combination of 365-day and 260-day calendars with 20-day months was used by other Nahua civilisations in central Mexico, such as the Maya.
Reading the Stone
At the centre of the stone is the face of a god. Exactly which god is debated, but most historians believe it is the sun god, Tonatiuh. Whoever it is, they have a knife for a tongue, and they hold a human heart in each of their clawed hands.
Four squares surround the central face. Each one represents a previous era. The Aztecs named these; Four Jaguar, Four Wind, Four Rain, and Four Water. It was believed that when each era ended, the world was destroyed and recreated.
For example, Four Jaguar lasted 13 Aztec centuries, or 676 years, before humanity was devoured by monsters. Four Rain lasted 6 Aztec centuries, or 312 years. The Aztecs believed they lived in the fifth age, and that like all ages, theirs would be destroyed because of its faults.
Moving outwards, the first ring features 20 symbols representing the days of the Aztec month. Each day was named and associated with a compass direction. For example, the first was Cipactli, the crocodile or alligator, and pointed east towards the rising sun.
Other names included; Calli (house, west), Xōchitl (flower, south), and Miquiztli (death, north) represented here by a skull. Like the days of the week, each month was dedicated to particular religious and agricultural festivals.
The second ring is something of a mystery. It's divided into squares with five dots. Above each of these sections are four small pointed symbols. The entire ring is then divided into eight segments, marked by large arrows, which probably represent the cardinal points.
The third ring is occupied almost entirely by two fire serpents, known as Xiuhcoatl. Their segmented bodies are covered in flames, and their open mouths hold human heads. Their symbolism is unknown, but they might be rival gods Quetzalcoatl and Tezcatlipoca.
At the very top of the stone is the date '13 Reed', while the centre of the stone bears the name Motecuhzoma II. This is believed to be the name of the ruler who commissioned the stone and the date to correspond to 1479 CE - the beginning of the fifth and current era.
Over the years, archaeologists and historians have pieced together fragments of evidence and managed to write a story of the sun stone.
We know that the stone would have been laid flat rather than standing upright, and that it was once painted in blue, red, green, and yellow. And while León y Gama thought that it might be a sundial, historians today believe that it might have been a sacrificial platform.
Yet despite centuries of inquiry and investigation, there is so much we don't know about this monument. Some of its most intriguing symbols still evade meaning.
These mysteries haven't stopped it from becoming a symbol of Mexican identity. The sun stone can be found everywhere; on coins and stamps, as well as graffiti and football kits.
It's funny to think that this monolith has seen its own life, death, and rebirth; created to emphasise Aztec power, discarded and desecrated by invaders, before being resurrected as a national monument.
Tap to explore
Take a look around the National Museum of Anthropology, Mexico City, where you can discover the artefacts of the Aztecs, Mayans, and more Mesoamerican peoples.
