The Expo introduced numerous urban best practices and concepts from all over the world which the organisers hope will be a lasting legacy for better urban life in China and around the world. It advocated for future development to focus on environmental sustainability, efficiency and diversity. The innovations and achievements of the event were summarised in the Shanghai Declaration issued by the participants of the Expo. The declaration also nominated the Shanghai Expo's closing day 31 October as "World Better Cities Day". United Nations Secretary-General Ban Ki-moon stated at the closing of the Expo, "Thanks to this Expo, millions of people learned about possibilities for making our cities healthier and safer, cities that better integrate nature and technology, cities that offer their citizens cleaner air and water, and better lives all around".