Tourists gather to watch the flag-raising ceremony at Tian'anmen Square during the three-day May Day holiday in Beijing, on May 1, 2012. [Photo/Xinhua]

Tourists watch the flag-raising ceremony at Tian'anmen Square during the May Day holiday in Beijing on May 1, 2012. [Photo/Xinhua]

Tourists crowd on the Great Wall during the May Day holiday in Beijing, April 29, 2012. [Photo/Xinhua]

People visit the Palace Museum in Beijing during the May Day holiday on April 30, 2012. [Photo/Xinhua]