Maintenance, conservation, and restoration are the various measures, actions and operations implemented to preserve any monument, respect its authenticity, and transmit it to the women and men of today and tomorrow. The Venice Charter, a fundamental treaty for the preservation and restoration of ancient buildings, was adopted by the International Congress of Architects and Technicians of Historic Monuments held in Venice in 1964. It provides a framework for interventions on historic monuments and sets out a number of definitions. Thus, the three complementary approaches to maintenance, conservation, and restoration can be summarized as follows:

Maintenance

Periodic preventive conservation actions that aim to maintain a property in an appropriate state so that it retains its heritage interest. The maintenance is carried out by :
  • a daily watch
  • regular cleaning of the circulation galleries, stairs, and spaces that make up the building
  • control of stormwater runoff and drainage such as gargoyle and gutter unclogging
  • functional maintenance of the building: doors, gates, locks, and electrical networks.

Conservation

A set of practices designed to prolong the life of a work of art or an art object; it requires the research and elimination of the causes of alteration. The conservation is thus divided into two aspects:
  • Preventive conservation by acting in particular on the urban environment with the reduction of pollutant emissions, on the search for the balance of the ecosystems that settle on the monument but also on the regular maintenance of the building.
  • Curative conservation by acting directly on the building and its materials in order to stop or limit the processes of degradation. These operations are multiple and adapted to each situation.

Restoration

Making exact copies, for stonecutting and exact copies, for sculpture, on a property in a stable or stabilized state, with the aim of improving its appreciation, understanding, and/or use, while respecting its heritage interest and the materials and techniques used. The restoration, therefore, consists of replacing architectural elements that have been too altered to be preserved with copies. These achievements are always based on documented sources.