Each year the International Day of Peace is observed around the world on 21 September. The General Assembly has declared this as a day devoted to strengthening the ideals of peace, both within and among all nations and peoples.

Here is a link to the message of the General Secretary of the United Nations on the International Day of Peace 2014: 
http://www.un.org/en/events/peaceday/2014/sgmessage.shtml