Pyramid of the Sun

Listen to the ground first. Under your shoes, loose volcanic gravel crunches with every step. The air up here is thin and dry, and the sun lands hard on the back of your neck. Ahead, a wide mountain of grey stone rises in stacked levels, its edges softened by centuries of wind and rain. This is the Pyramid of the Sun, at the heart of the ancient city of Teotihuacan, about fifty kilometres northeast of Mexico City.

Start with a strange fact. Nobody knows what the people who built this place called it. We do not know the name of their city, their rulers, or even the language they spoke with certainty. The name Teotihuacan comes from the Aztecs, who arrived centuries after the city had emptied. In their language, Nahuatl, it is usually translated as the place where the gods were created. The Aztecs found these ruins already ancient, and they treated them as sacred ground.

The pyramid itself was built in the early centuries of the Common Era, roughly in the first and second centuries. At that time, Teotihuacan was growing into one of the largest cities in the world. Archaeologists estimate that it held many tens of thousands of people at its peak. It had apartment compounds, workshops, painted walls, and a planned street grid. For several centuries, it shaped trade and politics across much of what is now Mexico and Central America.

Now look at the shape in front of you. The pyramid is often described as the third largest in the world by volume, after the great pyramid at Cholula, also in Mexico, and the Great Pyramid of Giza in Egypt. Its base is roughly comparable to the one at Giza, though it stands much lower. The core is not solid cut stone. It is mostly packed earth and rubble, held in place and then faced with stone.

Here is a detail most visitors miss. When this city was alive, the pyramid did not look grey. The stone surface was covered with a thick layer of plaster, and that plaster was painted. Traces of colour across Teotihuacan suggest that red was common. So try to picture it... a smooth, bright mountain shining in the sun, rising above a city of painted walls. The rough stone you see today is the skeleton, not the skin.

Turn and look along the wide avenue that runs beside the pyramid. The Aztecs called it the Avenue of the Dead, because they believed the low mounds along its sides were tombs. In fact, most of them were platforms for temples and buildings. The avenue runs for a long distance, with the Pyramid of the Moon at its northern end. The whole city was laid out with care, and its orientation shifts slightly away from true north.

That careful angle was not an accident. Researchers have argued that the layout of Teotihuacan connects to the movements of the sun across the sky, and to the shapes of the surrounding mountains. Some of these ideas are still debated. But it is clear that the builders thought about the land and the sky together. When you stand here, notice how the Pyramid of the Moon echoes the outline of the mountain behind it.

The second surprise lies underground. In 1971, archaeologists explored a tunnel beneath the pyramid. It leads from the base towards the centre, ending in chambers deep under the structure. The cave may have been important before the pyramid was built. Across Mesoamerica, caves were often seen as entrances to the underworld and places of creation. It is possible that the builders placed this huge monument directly over a sacred opening in the earth.

The pyramid you see today has also been shaped by modern hands. In the early twentieth century, a Mexican archaeologist named Leopoldo Batres led a major restoration here, timed around the centennial of Mexican independence. His team removed a large amount of material from the outer layers. Many later scholars criticised the work, because it changed the original profile and may have destroyed evidence. So part of what you see is ancient, and part is the result of that restoration.

A small thing to notice as you walk closer. In some sections of the stone facing, you may see tiny pebbles pressed into the mortar between larger stones. These mark areas rebuilt during restoration work, separating newer surfaces from older ones. Once you spot them, you start reading the walls differently. You can see where the past ends and where the twentieth century begins, written in small stones.

In 1987, the ancient city of Teotihuacan was added to the UNESCO World Heritage list. Today, people come for many reasons. Some come for archaeology. Some come for the view. On the spring equinox, large crowds often gather here, many dressed in white, hoping to feel the energy of the sun. This is a modern tradition rather than an ancient one, but it shows that this place still holds meaning for people.

For many years, visitors climbed to the summit. In recent years, access to the top has been restricted to protect the structure, so check the current rules when you arrive. Even from the base, the scale is clear. Remember that you are high above sea level here, more than two thousand metres. Walk slowly, drink water, and protect yourself from the sun. There is very little shade along the avenue.

Before you move on, stand still for a moment. Feel the heat coming up from the stones, and listen to the voices of vendors, the whistles of clay toys, and the wind across the open ground. People lived, worked, and prayed in this valley almost two thousand years ago, and then they left. We still do not fully understand why. As you walk away, look back once more at the pyramid's long, stepped outline against the sky.