Pyramid of the Sun: Teotihuacan's Monumental Great Pyramid

The Pyramid of the Sun is the largest monument of Teotihuacan, the ancient city north-east of modern Mexico City. Built mainly in the second century AD and largely complete by about AD 200, it rises some 65 metres above the Avenue of the Dead and ranks among the largest pyramids ever built in the Americas. Its scale, its precise alignment and the tunnel discovered beneath it make it a key to understanding one of the great cities of the ancient world.

Teotihuacan and its plan

Teotihuacan grew in the Valley of Mexico from about 100 BC. By AD 200–550 it was the largest city in the Americas, with a population usually estimated at around 100,000 people, though figures from about 50,000 to over 125,000 have been proposed. Its influence reached across Mesoamerica. In AD 378, a Teotihuacan-linked lord named Sihyaj K’ahk’ arrived at the Maya city of Tikal, an episode known as the Teotihuacan entrada, and a new dynasty with Teotihuacan ties took power there.

The city was carefully planned. Its main axis, the Avenue of the Dead, runs for more than two kilometres, and most buildings follow a grid oriented about 15.5 degrees east of true north. The Pyramid of the Moon closes the avenue’s northern end, and the Ciudadela, with the Temple of the Feathered Serpent, lies to the south. The Pyramid of the Sun stands on the east side, between the two.

Most of the population lived in large walled apartment compounds, each housing dozens of people. Some neighbourhoods were home to migrants from other regions, including the Oaxaca valley and the Gulf Coast, which shows how cosmopolitan the city had become.

The builders’ language and their own names for these places are unknown. Teotihuacan had a system of signs, but no long texts have survived that can be read.

Building the pyramid

Archaeologists date the main construction of the Pyramid of the Sun to roughly AD 100–200, based on pottery in its fill and radiocarbon dating. It was built in a few large campaigns rather than slowly over centuries.

The pyramid has a core of earth, rubble and sun-dried mud brick (adobe), held together by internal walls. This was faced with stone and covered with lime plaster, which was almost certainly painted, probably in red and other bright colours. A temple stood on the summit, reached by a steep staircase on the west side.

The structure rises in stepped tiers to a flat top. A platform attached to its west face, called an adosada, was added later. The whole monument stands within a large enclosed precinct surrounded by a platform.

Size and scale

These figures make it one of the largest structures of the ancient Americas. By volume it is smaller than the Great Pyramid of Cholula in Puebla, which was enlarged over many centuries, and smaller than the Great Pyramid of Giza in Egypt. The two types also differ: Mesoamerican pyramids were platforms for temples, not tombs built as solid monuments.

Materials came largely from the valley itself: volcanic stone, earth and clay. Without draught animals or wheeled transport, all of it was carried by human porters, basket by basket.

Building it required huge amounts of organised labour. Estimates of the workforce vary widely, but the project was clearly directed by a strong central authority able to feed and manage thousands of workers.

The cave and the tunnel

In 1971 archaeologists working at the foot of the western staircase found the entrance to a tunnel. It runs about 100 metres east, beneath the pyramid, ending in a series of chambers arranged roughly like a cloverleaf near the pyramid’s centre.

At first the tunnel was described as a natural lava tube. Later studies argued that it was largely dug or enlarged by people, much like other man-made tunnels found beneath Teotihuacan, many of which began as quarries for building stone. The tunnel was blocked in antiquity with walls and had been entered and partly emptied before modern discovery.

In 1975 Doris Heyden proposed that the cave was a sacred origin place. In later Aztec belief, caves were entrances to the underworld and places where peoples emerged. Many scholars think the tunnel was a holy site that helped determine where the pyramid was built.

Further research since 2008, led by Alejandro Sarabia of Mexico’s National Institute of Anthropology and History (INAH), tunnelled into the pyramid’s core and found offerings and evidence of earlier buildings on the site. These results suggest that the location was already important before the great pyramid was raised.

Meaning and orientation

The pyramid faces west, and its orientation is slightly skewed from the cardinal directions. Several scholars have argued that its alignment points to sunsets on dates around 29 April and 12 August. These dates divide the year in a way that may relate to the 260-day ritual calendar used across Mesoamerica, though not all researchers accept this interpretation.

The original dedication is unknown. The pyramid may have honoured a deity connected with water, fire, or the creation of the world. Some scholars link it to a storm god, others to an earth or fire deity. The name “Pyramid of the Sun” comes from the Aztecs, not its builders.

Whatever its dedication, the pyramid dominated the skyline of the city. Seen from the plazas below, its terraces would have framed ceremonies held on the summit temple, visible to thousands of people at once. Its position on the main avenue, near the tunnel and in line with the surrounding mountains, suggests the builders saw it as the centre of a sacred landscape.

Fire, decline and Aztec memory

Teotihuacan’s centre was burned and its power declined in the sixth or seventh century AD, with dates usually given between about AD 550 and 650. The burning focused on temples and elite buildings along the Avenue of the Dead, which has led some historians to suggest an internal revolt, though the cause is still debated. Other explanations include attack by outsiders, conflict among elite factions, and pressure from drought and failing harvests.

The city did not empty overnight. People continued to live among the ruins on a smaller scale for centuries, but Teotihuacan never regained its former power. Its fall opened the way for regional centres such as Xochicalco, Cholula and later Tula to rise in central Mexico.

Centuries later, the Aztecs, who rose to power in the fourteenth and fifteenth centuries, regarded the ruins with awe. They called the city Teotihuacan, a Nahuatl name often translated as “the place where the gods were created”. According to Aztec myth, the gods gathered there to create the present sun and moon. The Aztecs named the largest pyramid after the sun and made pilgrimages to the site. Objects in Teotihuacan style have been found among offerings at the Templo Mayor in Tenochtitlan, showing that the Aztecs collected and reburied relics from the ancient city.

Excavation and restoration

Between 1905 and 1910, the Mexican archaeologist Leopoldo Batres led a major project to clear and restore the pyramid in time for the centenary of Mexican independence. His team removed large amounts of material from the pyramid’s outer layers, in places several metres, believing they were later additions.

The work exposed the structure but is widely criticised today because it destroyed original surfaces and altered the pyramid’s shape. Later archaeologists, including Jorge Acosta, carried out more careful work. In the 1960s René Millon’s Teotihuacan Mapping Project produced a detailed map of the entire city, transforming knowledge of how Teotihuacan was organised.

In 1987 the Pre-Hispanic City of Teotihuacan was inscribed as a UNESCO World Heritage Site.

Myths and facts

Myth: The Pyramid of the Sun was built by the Aztecs. Fact: It was built more than a thousand years before the Aztec empire, by the people of Teotihuacan.

Myth: It was a tomb, like the Egyptian pyramids. Fact: It was a platform for a temple. No royal tomb has been found inside it, although burials and offerings were placed at points during its construction, as at other Teotihuacan monuments.

Myth: Standing on top at the spring equinox gives special energy. Fact: Large crowds gather each March, but this is a modern custom. There is no evidence the builders aligned the pyramid to the equinox.

Timeline

• c. 100 BC: Teotihuacan begins to grow as a major settlement.
• c. AD 100–200: Main construction of the Pyramid of the Sun.
• c. AD 200–550: Teotihuacan at its height as the largest city in the Americas.
• c. AD 550–650: Burning of the city centre and decline.
• 14th–15th centuries: Aztecs revere the ruins and name the pyramid.
• 1905–1910: Leopoldo Batres clears and restores the pyramid.
• 1971: The tunnel beneath the pyramid is discovered.
• 1987: Teotihuacan becomes a UNESCO World Heritage Site.

Why it matters

The Pyramid of the Sun shows the ambition and organising power of Teotihuacan at its height. It shaped the city’s layout, influenced architecture across Mesoamerica and, long after the city fell, remained a sacred place in the memory of later peoples such as the Aztecs.