German President Horst Koehler attended "Sino-German World Expo City Forum" which was held in Hamburg House of World Expo on May 20, 2010. Four people in  total were invited to the forum, including German President Horst Koehler, Prof. Tang Zilai of Tongji University, Germany Architect Ms. Weiss, and President Mao Yushi of Unirule Institute of Economics. 

 
Prof. Mao Yushi gave his opinion on the following three aspects. Firstly, China's urbanization pace will be fastened. As urban population keeps increasing, more and more employment opportunities are created, and more rural population are attracted into cities. Secondly, China's income gap is rather large at present, resulting in diversified housing demand in future cities. Since the government does not permit the existence of slums, we have to pay special attention as to how to meet the housing need of low-income population in cities. Thirdly, China's pace into aging society will also be fastened due to family planning. Proportion of elders will rise quikly, which will exert certain influence on city planning.