The idea of creating an international movement for protecting sites in other countries emerged after World War I.

The Convention concerning the Protection of the World Cultural and Natural Heritage developed from the merging of two separate movements: the first focusing on dangers to cultural sites, and the other dealing with conservation of nature.

The event which aroused particular international concern was the decision to build the Aswan High Dam in Egypt, which would flood the valley containing the Abu Simbel temples, a treasure of ancient Egyptian civilization. In 1959, after an appeal from the governments of Egypt and Sudan, UNESCO decided to launch an international campaign. Archaeological research in the areas to be flooded was accelerated. Above all, the Abu Simbel and Philae temples were dismantled, moved to dry ground and reassembled.

The campaign cost about US$ 80 million, half of which was donated by some 50 countries, showing the importance of nations' shared responsibility in conserving outstanding cultural sites. Its success led to other safeguarding campaigns, such as Venice in Italy, Moenjodaro in Pakistan and Borobodur in Indonesia to name but a few.

Consequently, UNESCO initiated, with the help of the International Council on Monuments and Sites (ICOMOS), the preparation of a draft convention on the protection of cultural heritage.

The idea of combining conservation of cultural sites with those of nature comes from the United States. A White House Conference in Washington, D.C., in 1965 called for a "World Heritage Trust" that would stimulate international cooperation to protect "the world's superb natural and scenic areas and historic sites for the present and the future of the entire world citizenry". In 1968 the International Union for Conservation of Nature (IUCN) developed similar proposals for its members. These proposals were presented to the 1972 United Nations conference on Human Environment in Stockholm.

Eventually, a single text was agreed upon by all parties concerned. The Convention Concerning the Protection of World Cultural and Natural Heritage was adopted by the General Conference of UNESCO on 16 November 1972.

By regarding heritage as both cultural and natural, the Convention reminds us of the ways in which people interact with nature, and of the fundamental need to preserve the balance between the two.

The most significant feature of the World Heritage Convention is to link together in a single document the concepts of nature conservation and the preservation of cultural sites. Nature and culture are complementary and cultural identity is strongly related to the natural environment in which it develops.

The Convention defines the kind of natural or cultural sites which can be considered for inscription on the World Heritage List, and sets out the duties of States Parties in identifying potential sites and their role in protecting and preserving them. By signing the Convention, each country pledges to conserve not only the World Heritage sites situated on its territory, but also to protect its national heritage.

The State Party is encouraged to integrate the protection of the cultural and natural heritage into regional planning programmes and adopt measures which give this heritage a function in the day-to- day life of the community.

The Convention further describes the function of the World Heritage Committee, how its members are elected and their terms of office, and specifies the professional advisory bodies to which it can turn for advice in selecting the sites to be listed.

The Convention explains how the World Heritage Fund is to be used and managed and under what conditions international financial assistance may be provided.

The application for a site to be inscribed in the World Heritage List must come from the country itself. UNESCO makes no recommendations for listing. The application has to include a plan detailing how the site is managed and protected.

The World Heritage Committee meets once a year and examines the nominations on the basis of technical evaluations. These independent evaluations of proposed cultural and natural sites are provided by two advisory bodies, the International Council on Monuments and Sites (ICOMOS) and the World Conservation Union (IUCN), respectively.

A third advisory body, the International Centre for the Study of the Preservation and Restoration of Cultural Property (ICCROM), provides expert advice on restoring monuments and organizes training courses.

Once a site is selected, its name and location are placed on the World Heritage List.

To be included on the World Heritage List, sites must satisfy the selection criteria. These criteria are explained in the Operational Guidelines for the Implementation of the World Heritage Convention which, besides the text of the Convention, is the main working document on World Heritage. The criteria have been revised regularly by the Committee to match the evolution of the World Heritage concept itself.

Cultural properties should:

i. represent a masterpiece of human creative genius; or

ii. exhibit an important interchange of human values over a span of time or within a cultural area of the world, on developments in architecture or technology, monumental arts, town-planning or landscape design; or

iii. bear a unique or at least exceptional testimony to a cultural tradition or to a civilization which is living or has disappeared; or

Natural properties should:

Mixed sites have both outstanding natural and cultural values. Since 1992 significant interactions between people and the natural environment have been recognized as cultural landscapes.