Enrique X de Anda, Jorge Alberto Manrique, Augusto Molina and Louise Noelle

Introduction

The present document, while containing certain general concepts, focuses specifically on the historic and monumental heritage of the Mexican Republic. Nevertheless, it can be made extensive to other geographic and cultural regions with similar characteristics. For the purpose of analysis and to follow the Nara recommendations, we considered segregating into five points the evaluation and characteristics of authenticity and the limitations of possible interventions. However, the value of authenticity must be considered as a single totality. Thus, neither evaluation nor interventions can focus on some aspects in detriment of others, but it is true that within the balance that historic authenticity must maintain, some of aspects may be predominant.

This document is based on the current and regional interpretation of the Venice Charter, the Charter for Historic Towns, various documents issued in ICOMOS meetings and especially, the Charters of the Inter-American Symposia of ICOMOS Mexico, as well as the cumulative experience of those who have intervened in the heritage resources of Mexico.

1. Materials and Techniques

In monuments and historic sites, materials (structural, finishes and decorative) are considered authentic if they are the ones used in the original fabric or if they were integrated during a significant stage of their history. In addition, materials must retain the same function and remain in situ. Finally, materials must maintain the same expressive intent given to them by their creators. As to techniques [manufacture, assemblies] utilized in these or other materials, those belonging to the original creation or resulting from modifications carried out during significant periods will be considered authentic.

All interventions in a monuments or site must retain the original materials as long as it is feasible to do so within current circumstances. Likewise, original construction techniques will also be preserved when handling those materials. Following the spirit of the Venice Charter, contemporary materials and techniques are allowed when these are indispensable to the permanence of the monument. There is always a preference for the use of the original materials or materials similar to them, as well as for surviving traditional crafts, which also helps foster traditional construction. In all cases the modification of materials and techniques must remain patent.

2. Structure

The structural system and its original function are integral parts of the authenticity of a monument.

Interventions must take into account this function lest they modify the structural systems, except in cases when it is indispensable for the monument's stability.

3. Form and Design

The authenticity in form and design in a monument must correspond to the author's intention. Also authentic are alterations that are acceptable because of their quality and historic importance, as long as they have been properly integrated into the site or monument, even when the original design was altered.

Interventions will be based on a careful historical and aesthetic diagnosis to determine which elements are original and which of the elements that later altered the original design possess the value of authenticity and must be retained. This diagnosis will be based on archaeological work as well as graphic and written documentation, all conducted according to the critical academic techniques accepted in historic research. When certain elements are no longer extant but sufficiently documented, there will be an open discussion to decide their substitution with elements that approach the original (in which case there will always be a testimony of the intervention) or with elements that are contemporary in design.

4. Use and Function

The authenticity of a monument or site is increased when the original function is continued and corresponds to the present use. It is also authentic, though to a lesser degree, when a change in use is dignified and compatible with the original and total reading of the building.

Any intervention that will change the original or the historic functions of a monument or site must conform to the spirit of the building and must allow for a return to the original use. This implies the conservation of the original spaces, design and materials. When preceded by an evaluation of the historic and aesthetic values, minimal modifications required for the new use [will be permitted].

5. Context

All considerations of authenticity must include the natural and built environments, as well as the cumulative historic context in which the monument or site is located. Loss of the surrounding environment affects [the monument's] value. Cultural elements are also inseparable from the material context.

Interventions cannot refer exclusively to a monument or group of monuments, but must include integrally the setting, including all the values of its authenticity. In addition, it is necessary to go beyond the cumulative historic context to include visual aspects, avoiding alterations and additions that will affect the overall integrity.