A specialist introduces the damage and restoration of an antique clock at the Palace of Blessings to Mother Earth (Yi Kun Gong) in the Palace Museum in Beijing on May 5, 2013. [Photo/Lin Hui]

Beijing's Palace Museum Curator Shan Jixiang (center) simulates how a visitor broke a window and damaged an antique clock at the Palace of Blessings to Mother Earth (Yi Kun Gong) in the Palace Museum in Beijing on May 5, 2013. A male tourist broke the window and the window damaged an antique clock on Saturday. [Photo/Lin Hui]