World Heritage Day is being obsereved today with the theme : sustainable tourism. The day aims to spread awareness of the importance of protecting and preserving various sites around the world that have achieved world heritage status. <br/><br/>Urban Development minister M Venkaiah Naidu? said that it's our duty to protect and preserve India's rich wealth of heritage. <br/><br/>World Heritage sites are officially recognised by the UN and the United Nations Educational Scientific and Cultural Organisation, UNESCO. These sites are classified as a natural or man-made structure that has international importances and hold cultural and physical significance. <br/><br/>There are total 1,052 heritage sites in all over the World. In India, there are 35 World Heritage Sites including the very famous Taj Mahal in Agra, Nalanda University, Mahabodhi Temple in Bihar and Khajuraho in Madhya Pradesh. <br/><br/>In Delhi, different aspects of the national capital's heritage will be brought to the fore during a week-long celebration for World Heritage Day, beginning today. The celebration will witness a series of events that will offer people insights about the city's heritage.