To celebrate World Heritage Day, children from 21 schools across the city assembled at world heritage site Humayun's Tomb on Wednesday. The event had been organized by Aga Khan Trust for Culture which had planned a dual celebration of World Heritage Day which is on Friday and Earth Day next week. They organized a series of events integrating heritage and environment for over 1,200 kids. There are 30 sites in India on the world heritage list-the Tomb, Red Fort and Qutub Minar from Delhi among them.