Archaeologists have discovered a possible ossuary containing human remains beneath Mexico City during construction of the Mexico City–Querétaro passenger railway.
The discovery was made near the Buenavista terminal as part of archaeological salvage work conducted by Mexico's National Institute of Anthropology and History (INAH).
Researchers have so far recovered remains representing nine individuals, including two showing evidence of cranial modification, alongside pottery, obsidian blades and objects associated with domestic activities.
Preliminary evidence suggests the deposit could date to the Late Postclassic period (AD 1200–1519), the period of contact with the Spanish (AD 1519–1535), or potentially the early colonial period.
Human remains discovered beneath Mexico City
The first skeletal remains were encountered on 17 September 2026 during earthworks for the new railway.
Archaeologists excavated to approximately 1.4 metres below the surface, uncovering skulls, jawbones, pelvic bones, fragments of femurs, ribs and teeth.
Further excavation revealed a concentration of human bones without anatomical articulation – meaning the bones were no longer arranged as complete skeletons.
This led archaeologists to interpret the deposit provisionally as an ossuary, where human remains from earlier burials may have been gathered and reinterred.
Nine individuals have so far been identified, together with five additional mandibles and large bones including radii, tibias and parts of the pelvis.
Two of the individuals display cranial modifications, although the precise form of the alterations has yet to be established.
Laboratory analysis will attempt to determine the age and sex of the individuals and examine the modifications in greater detail.
Aztec-period artefacts found with the bones
Archaeologists also recovered pottery associated with the Aztec III period, dating approximately from AD 1350 to 1520.
The ceramics are predominantly domestic and include plates, cooking pots and containers associated with extracting salt from the former Lake Texcoco.
Seven miniature spindle whorls and two figurines were also discovered.
Stone objects include four fragments of metates, grinding implements and obsidian blades.
Most of the obsidian is green and may have originated from the Sierra de las Navajas in the modern Mexican state of Hidalgo.
The combination of pre-Hispanic artefacts and human remains complicates the dating of the deposit.
Researchers currently consider it possible that the bones were gathered during the final decades of the pre-Hispanic period, around the time of Spanish contact, or during the subsequent colonial era.
Ancient neighbourhood of Tlatelolco
The location could provide an important clue to understanding the deposit.
The remains were discovered within what was once the calpulli of Nonoalco, one of 19 pre-Hispanic neighbourhoods associated with the island settlement of Tlatelolco.
A calpulli was a local social and territorial community within Nahua society, often comprising families who shared land, obligations and aspects of communal organisation.
The discovery could therefore provide evidence for funerary practices among inhabitants of Nonoalco during a period of major cultural and political change.
“This hypothesis is reinforced by the fact that the discovery occurred within what was the calpulli of Nonoalco, one of the 19 pre-Hispanic neighbourhoods on the islet of Tlatelolco, which could offer information about the funerary practices of the time,” said José Manuel Cervantes Pérez, head of INAH's Physical Anthropology Laboratory.
Possible reburial of earlier graves
Another important element is the nearby church of San Miguel Nonoalco.
The church was constructed during the 16th century and served as a visiting chapel for Franciscan friars associated with the Convent of Santiago Tlatelolco.
Researchers note that other ossuaries discovered in Mexico City have been associated with the colonial or Spanish-contact periods, while the newly discovered deposit also contains material dating to the pre-Hispanic era.
Physical anthropologist Abril Machain Castillo said the types of bones recovered support the ossuary interpretation.
Rather than containing every element of complete skeletons, the deposit is dominated by larger, more durable bones such as skulls and long bones.
One possibility is that the individuals were originally buried elsewhere before their graves were disturbed or cleared for subsequent burials. Selected remains may then have been collected and placed together in the secondary deposit.
This interpretation has not yet been conclusively established, and further study will be required to determine when and why the bones were moved.
Laboratory analysis could establish date
The remains and artefacts have now been transferred to project laboratories in Tula de Allende and Tepeji del Río Ocampo (Hidalgo).
Experts will clean, conserve and analyse the human remains, ceramics and stone artefacts before they are put into permanent safekeeping.
Physical anthropology could yield demographic information about the individuals; ceramics and archaeological context may narrow date of deposit further.
Knowing if the possible ossuary dates to the last years of pre-Hispanic Tlatelolco, the period after the arrival of the Spaniards or the colonial era will be very important.
If it is confirmed as an ossuary then the discovery could reveal how communities living around Tlatelolco treated and reorganised their dead during one of the most transformative periods in Mexico City’s history.
Sources : INAH