Thank you very much for the nice cover
This stamp set is dedicated to the Expo 2010 held in Shanghai China. Here there are some more information from Wikipedia, the free encyclopedia;
Expo 2010 (simplified Chinese: 2010上海世界博览会) will be held in Shanghai, China and is a scheduled World Expo in the grand tradition of international fairs and expositions. The theme of the exposition will be "Better City – Better Life" and signifies Shanghai's new status in the 21st century as a major economic and cultural center. It is expected to generate the largest number of visitors in the history of the world's fairs in terms of gross numbers.
The Expo will take place from May 1 – October 31, 2010.
For the first time in history, the Shanghai 2010 Expo will feature a highly sophisticated online version called "Online Expo Shanghai".
Massive construction of new metro lines have been undertaken for years in order to serve the traffic demands of the event. Shanghai Metro Line 7, Shanghai Metro Line 8 South Extension, Shanghai Metro Line 13 are all under construction and will connect the expo site directly with the other parts of the city. Shanghai Metro Line 9 Phase II, Shanghai Metro Line 11 Phase I, Shanghai Metro Line 2 East Extension, Shanghai Metro Line 10 will be opened before the event too.http://en.wikipedia.org/wiki/Expo_2010