Archaeologists from Mexico’s National Institute of Anthropology and History (INAH) have completed the first comprehensive altimetric survey of the area once occupied by the sacred precinct of the Aztec capital, Mexico-Tenochtitlan, in a project designed to identify buried pre-Hispanic structures beneath the streets of Mexico City’s Historic Centre.
The survey forms part of the Institute’s Urban Archaeology Programme (PAU) and is expected to improve the protection of archaeological remains during future infrastructure and construction projects.
Rather than relying solely on excavation, researchers recorded subtle changes in ground elevation, street gradients, building inclinations and structural cracks across the historic centre. These surface anomalies may reflect the location of walls and foundations from the former ceremonial precinct, which was largely buried following the Spanish conquest in the 16th century.
According to PAU director Raúl Barrera Rodríguez, previous excavations have demonstrated a correlation between visible fractures in modern buildings and buried archaeological remains.
“In earlier investigations, excavations carried out beside structural cracks revealed the edges of pre-Hispanic foundations,” Barrera explained. “By documenting these fractures and variations in ground level, it becomes possible to propose the layout of the buildings that once formed the sacred precinct.”
The study area covers about 450 metres on each side of the former ceremonial complex, and spans a portion of Mexico City’s historic centre. It includes the streets of San Ildefonso and Luis González Obregón to the north, Correo Mayor and El Carmen to the east, the northern edge of the National Palace and the area in front of the Metropolitan Cathedral to the south, and Monte de Piedad and República de Brasil to the west.
Fieldwork began in May 2025 and concluded in March 2026. Survey teams established thousands of elevation points along streets, property boundaries and street corners, adjusting the density of measurements according to changes in the terrain. Areas with noticeable rises or depressions were recorded at shorter intervals to improve accuracy.
The survey was carried out using Leica and Sokkia total stations, together with topographic GPS equipment capable of recording measurements with millimetre precision. The resulting data were processed using AutoCAD to create a detailed digital terrain model.
According to survey archaeologist Roberto Martínez Meza, the project builds upon decades of archaeological excavations carried out throughout the Historic Centre, where recurring patterns between modern structural deformation and buried architecture have been observed.
The information collected will be combined with historical documentation, previous excavations and archaeological records to produce a predictive map identifying where buried monuments and architectural remains are most likely to survive beneath the modern city.
Researchers believe the model will become an important planning tool, allowing archaeologists to predict the presence of pre-Hispanic remains before construction work starts and minimize accidental damage to one of Mexico’s most important archaeological landscapes.
Claudia Curiel de Icaza, the Secretary of Culture of Mexico, described the project as “an unprecedented investigation that will contribute to a fuller picture of the surviving traces of Tenochtitlan below the modern capital and will help to maintain the city’s archaeological heritage for the long term.”
The survey was undertaken by members of the Urban Archaeology Programme in collaboration with INAH’s Directorate of Public Registry of Monuments and Archaeological Zones, with contributions from archaeologists, architects, survey specialists and technical staff.
Header Image Credit : steban De Armas – Shutterstock
Sources : INAH
