Elgin Marbles restitution in international law

The essence of the thesis is this question- The question is what should happen to art or cultural property when a country demands its return from a country or museum that currently possesses the object for hundred of years? (TO BE ANSWERED IN THE CONTEXT OF THE TOPIC)

International law:

United Nations Educational, Scientific, and Cultural Organisation (UNESCO) set up the 1970 convention to control the illicit trafficking of cultural property

Unidroit Convention on Stolen or Illegally Exported

Cultural Objects 1995

1954 Hague Convention

http://scholarship.law.berkeley.edu/cgi/viewcontent.cgi?article=1874&context=californialawreview

http://rbdi.bruylant.be/public/modele/rbdi/content/files/RBDI%201986/RBDI%201986-2/Etudes/RBDI%201986.2%20-%20pp.%20327%20%C3%A0%20338%20-%20Anneliese%20Monden%20et%20Geert%20Wils.pdf

http://www.art-law.org/centre/recherches/fns/jdiCornu-Renold-en.pdf

http://blogs.law.harvard.edu/hnmcp/files/2012/02/Fisher-Sander-Paper-Winner-FINAL-Strother-Resolving-Cultural-Property-Disputes-in-the-Shadow-of-the-Law.pdf

http://iplj.net/blog/wp-content/uploads/2013/09/C04_Fincham.pdf

http://docs.law.gwu.edu/stdg/gwilr/PDFs/41-1/41-1%20Doyle.pdf