Organic Relationship between Architecture and Decorative Elements: Challenges in the Conservation of the AztecSkull Altar, Mexico City

The Altar of Skulls is located in the Historical Centre of Mexico City, part of the Sacred Precinct of Tenochtitlan built by the Aztecs. This Archaeological site is considered by UNESCO asCultural Heritage of Humanity.The Altar of Skulls contains a core of igneous stones, with walls made of rock wedges carved in the shape of skulls, covered with lime mortars, with remains of red and yellow polychromy. The building is composed of approximately 264 skulls. It is an example of the organic relationship that a stone object maintains with architecture in its constructive, formal, spatial and symbolic aspect. Many factors contribute to the deterioration of the site, all related to its geographical location within the valley of Mexico and the historical processes through which it has passed. The integrity and stability of the Altar of Skulls are affected by the slumping of the land caused by draining of the lake; previous archaeological and restoration interventions; and environmental conditions including factors such as humidity, temperature, light and the highly polluted environment. The knowledge obtained allows us to propose solutions to diminish the main causes of deterioration. It is a clear example of the need to inspect the environment, architecture and decorative elements in an organic multidisciplinary way.