UNESCO adopted an international treaty called the "Convention concerning the Protection of the World Cultural and Natural Heritage" in 1972. The main mission is to encourage the identification, protection and preservation of cultural and natural heritage around the world considered to be of outstanding value to humanity. Towards this purpose the World Heritage Committee has established a World Heritage List, and thus undertakes responsibility to preserve the nature and cultural heritage for the future. At present there are approximately 900 sites included in the List.