Teotihuacan is a ruined city about 40 km north-east of Mexico City that, at its height around 300–550 CE, housed an estimated 100,000 to 150,000 or more people, making it one of the largest cities in the world at the time. It is known for the Pyramid of the Sun, the Pyramid of the Moon, the Avenue of the Dead and the Temple of the Feathered Serpent. Its builders left no deciphered writing, so their own name for the city and the language they spoke are still unknown.
That silence is why Teotihuacan draws archaeologists and alternative researchers alike: a planned, sky-aligned metropolis with liquid mercury sealed beneath one temple and mica built into its structures, and no surviving text explaining any of it. This guide sets out what excavation has actually found, what remains genuinely open, and how Billy Carson reads the site, so fans and skeptics can weigh the same evidence side by side.
Where is Teotihuacan and what does the name mean?
Teotihuacan sits in the north-east of the Basin of Mexico, about 40 km from the centre of Mexico City, and has been a UNESCO World Heritage Site since 1987. The name is Nahuatl, the language of the Aztecs (Mexica), who arrived in the region centuries after the city had been abandoned. It is usually rendered as "the place where the gods were made" or "the place where men become gods."
The name is therefore a later interpretation. The Aztecs found the ruins already ancient and folded them into their own sacred history; what the original inhabitants called their city has not been established.
What is clear is that the city was cosmopolitan. Most residents lived in apartment compounds, walled multi-family residential blocks, and excavations in these compounds have identified neighbourhoods of people from other regions, including a Zapotec enclave with ties to Oaxaca and barrios linked to the Maya area and the Gulf Coast. Traces of Teotihuacan-era settlement also keep turning up across the wider valley, as in 4BK's report on [a 1,500-year-old Teotihuacan village found in the heart of Mexico City](/the-discovery-of-a-1-500-year-old-teotihuacan-village-in-the-heart-of-mexico-city).
When was Teotihuacan built, and why did it decline?
Teotihuacan grew from a settlement founded around 100 BCE, with most of its monumental construction happening between roughly 100 and 250 CE. The city peaked between about 300 and 550 CE, when it covered some 20 km² and held an estimated 100,000 to 150,000 or more people.
Around 550 CE the ceremonial centre was burned and many of its major buildings damaged. By roughly 650–750 CE the city had largely emptied. Who set the fires and why is still argued: some researchers favour an internal uprising against the ruling elite, others an outside attack, and environmental and economic strain are often discussed as contributing factors. The burning is well documented; its cause is not.
The Avenue of the Dead and the Pyramid of the Sun
The Avenue of the Dead (Calzada de los Muertos) is the city's main axis, a broad ceremonial roadway about 2.5 km long that runs from the Pyramid of the Moon southward past the Pyramid of the Sun to the great enclosure known as the Ciudadela. Like the city's name, the avenue's name is a later label, reflecting the belief that the platforms lining it were tombs.
The avenue, and the street grid built around it, is oriented about 15.5° east of north rather than to true north. Because that deviation runs through the whole urban plan, it was clearly deliberate, and it sits at the centre of every serious discussion of the city's astronomy.
The Pyramid of the Sun is the largest structure in the city, rising roughly 65–70 m from a base about 220–225 m per side. In 1971 a team working under Jorge Acosta found a tunnel beneath it leading to a series of chambers, and archaeologists have since debated how much of that underground space is natural and how much was cut or shaped by hand. Either way, the pyramid was built directly over it, and since caves in Mesoamerican belief were places of origin and entrances to the underworld, the placement reads as a deliberate sacred choice.
The Pyramid of the Moon and the Temple of the Feathered Serpent
The Pyramid of the Moon, about 43 m high, closes the northern end of the Avenue of the Dead. Excavations led by Saburo Sugiyama and Rubén Cabrera showed that it was enlarged in a series of building stages, and that several of those stages were accompanied by dedicatory burials: sacrificed captives placed together with animals and rich offerings.
At the southern end of the avenue, the Ciudadela encloses the Temple of the Feathered Serpent, often called the Temple of Quetzalcoatl. The name Quetzalcoatl comes from the later Aztec pantheon; the temple's facade carries carved feathered-serpent heads alongside a second motif whose identity scholars still debate. Excavations in the 1980s found more than 200 sacrificial burials associated with the temple's construction around 200 CE, many of the individuals with their hands apparently bound behind their backs. These finds, analysed at length in Sugiyama's work, overturned an older picture of Teotihuacan as a peaceful theocracy and showed a state that used large-scale ritual killing to consecrate its monuments.
The tunnel beneath the Feathered Serpent: mercury, pyrite and offerings
In 2003 a sinkhole opened at the foot of the Temple of the Feathered Serpent, and archaeologist Sergio Gómez Chávez found that it led into a sealed tunnel. His team first surveyed it with small robots, including one named Tlaloc II, and then spent more than a decade excavating it, with work continuing to 2015 and beyond. The tunnel runs about 100 m and reaches roughly 18 m below the surface, ending beneath the temple itself.
Parts of the walls were coated with pyrite, a metallic mineral that glitters in low light. Liquid mercury was recovered near the far end. The fill held rubber balls, jaguar remains, greenstone figures and, in total, tens of thousands of objects. The excavators have interpreted the tunnel as a ritual evocation of the underworld, deliberately sealed after use. The discoveries are summarised in 4BK's earlier piece on [the 1,800-year-old offering to the gods found beneath the pyramid](/1-800-year-old-offering-to-the-gods-discovered-beneath-pyramid-of-teotihuacan).
The mercury deserves a careful reading. Liquid mercury can be produced by heating cinnabar, a red mercury ore that Mesoamerican peoples used as a pigment, and small quantities of mercury have also been found at a handful of Maya sites. Its placement in a sealed sacred space was deliberate, but its purpose is not recorded; most archaeologists point to its mirror-like surface.
The mica at Teotihuacan: what was found and what is known
Mica is a group of silicate minerals that split into thin, flexible, often transparent sheets that resist heat and do not conduct electricity. Those properties are why mica is used today as an insulator in electronics, and why its appearance at Teotihuacan has drawn so much attention. The details are covered in 4BK's report on [the mica, a material used today in electronics, found in the ancient city](/37-kilograms-of-mica-used-today-in-electronics-found-in-the-ancient-city-of-teotihuacan).
Two finds are usually cited. In the early twentieth century Leopoldo Batres, whose restoration of the Pyramid of the Sun is still criticised for removing original fabric, reported sheets of mica in the pyramid's upper levels. Separately, in the Viking Group, a complex along the Avenue of the Dead, excavators found two layers of mica laid one above the other beneath a floor, which is why the building is often called the Mica Temple.
Neither the source nor the purpose is settled. A popular claim holds that the mica came from Brazil, but that is not established; the nearest known sources are in Oaxaca and elsewhere in central Mexico, making a regional origin the simpler explanation. As for purpose, layers hidden under a floor were not decorative in any obvious way. Suggestions that the mica served as insulation, shielding or part of a device are speculation, and so are ritual explanations; the builders left no account. What can be said is that a city that lined a sacred tunnel with glittering pyrite and placed liquid mercury in it clearly valued reflective materials, and mica fits that pattern.
Alignments, the Aztec sun story and the Orion comparison
The 15.5° orientation of the city is linked by archaeoastronomers to sunsets on specific dates, around 12–13 August and 29–30 April, when the sun sets on the city's east–west axis. Pecked-cross markers, circles of small holes carved into floors and rock outcrops, have been tied to the same orientation, and some researchers connect the layout to the setting of the Pleiades. Anthony Aveni is among the scholars who have documented these markers.
The Aztecs revered the ruins long after the city fell. In the creation account known as the Legend of the Suns, and in the version recorded by Bernardino de Sahagún in Book 7 of the Florentine Codex, the gods gathered at Teotihuacan to create the present sun: Nanahuatzin threw himself into a fire and rose as the sun, and Tecuciztecatl followed and became the moon. The Tepantitla murals, with the figure often called the Great Goddess, have been read as a paradise of the rain god Tlaloc.
The Orion comparison comes from outside archaeology. Robert Bauval proposed that the three main pyramids at Giza mirror the three stars of Orion's Belt, and Graham Hancock popularised the idea that Teotihuacan's three principal monuments echo the same pattern (see our guide to [the Giza plateau and what lies beneath it](/the-giza-plateau-explained-a-visitors-guide-to-the-pyramids-sphinx-and-what-lies-beneath)). Critics note that the fit is loose: the Temple of the Feathered Serpent is a very different kind of structure from the two great pyramids, and the positions do not match the belt stars closely. Teotihuacan belongs to a small set of sites, alongside [the Nazca lines of Peru](/the-nazca-lines-explained-who-made-them-how-and-what-they-were-for), where planning at the scale of a landscape invites questions about what the builders were looking at.
Billy Carson's reading
Billy Carson has toured Teotihuacan, and his interpretation begins where the excavation reports stop. He draws a parallel between the layouts of Giza, Teotihuacan and Orion's Belt, treating the correspondence as evidence of shared knowledge between distant ancient cultures rather than coincidence. The comparison itself was popularised by Graham Hancock, and mainstream archaeologists regard the match as too loose to carry weight; readers should hold both views in mind.
Carson also reads the mica and the liquid mercury as signs of technology, not only of ritual. In his reading, an electrically insulating mineral laid beneath floors and a liquid metal sealed beneath a temple point to a purpose the conventional record has not explained. The archaeological position is that both materials are consistent with a ritual culture that prized reflective substances, and that no device or wiring has been found. Carson's reading asks why those specific materials were chosen, and that question is fair even for readers who do not accept his answer. The wider argument is explored in [Teotihuacán: City of the Gods or Ancient Spaceport?](/teotihuacán-city-of-the-gods-or-ancient-spaceport) and in the podcast conversation with Timothy Hogan on Teotihuacan and the secrets of Mexico.
Watch, read and go deeper
To see sites like this one explored on screen, start with the [Ancient Enigmas series on 4BK TV](/watch/ancient-enigmas). The 4biddenknowledge Podcast episode with Timothy Hogan goes further into the site's esoteric history. For the broader question of who taught ancient civilisations to build on this scale, the [Anunnaki and Sumer topic hub](/topics/anunnaki) collects Billy's work on ancient origins in one place.
Frequently asked questions
What does Teotihuacan mean?
Teotihuacan is a Nahuatl name given by the Aztecs, usually translated as "the place where the gods were made" or "the place where men become gods." The Aztecs arrived centuries after the city was abandoned, so the name reflects their beliefs about it. The original inhabitants' name for the city is unknown.
Who built Teotihuacan?
Teotihuacan was built by a people whose own name and language are not known, beginning around 100 BCE, with most monumental construction between about 100 and 250 CE. It was not built by the Aztecs, who came much later and treated the ruins as sacred. The city was home to residents from several regions, including Zapotec, Maya and Gulf Coast communities.
Is there really liquid mercury under Teotihuacan?
Yes. Archaeologist Sergio Gómez Chávez's team recovered liquid mercury from the tunnel beneath the Temple of the Feathered Serpent, which was discovered in 2003 and excavated over more than a decade. Mercury can be made by heating the ore cinnabar. Its purpose at Teotihuacan is not recorded; many archaeologists link it to the ritual use of reflective materials.
Why was mica found at Teotihuacan?
Mica sheets were reported in the Pyramid of the Sun's upper levels in the early twentieth century, and layers of mica were found beneath a floor in the Viking Group, often called the Mica Temple. Why it was placed there is unknown. The claim that it came from Brazil is not established, since mica sources exist in Oaxaca and central Mexico, and explanations ranging from ritual to insulation remain speculative.
Sources and further reading
- George L. Cowgill, Ancient Teotihuacan: Early Urbanism in Central Mexico (Cambridge University Press, 2015)
- Saburo Sugiyama, Human Sacrifice, Militarism, and Rulership: Materialization of State Ideology at the Feathered Serpent Pyramid, Teotihuacan (Cambridge University Press, 2005)
- Esther Pasztory, Teotihuacan: An Experiment in Living (University of Oklahoma Press, 1997)
- René Millon, Urbanization at Teotihuacán, Mexico, vol. 1, The Teotihuacán Map (University of Texas Press, 1973)
- Bernardino de Sahagún, Florentine Codex, Book 7, translated by Arthur J. O. Anderson and Charles E. Dibble
- Anthony F. Aveni, Skywatchers (University of Texas Press, 2001)
- Graham Hancock, Fingerprints of the Gods (1995)
