A US woman walks past the cement barriers outside Captiol Hill in Washington, Sept. 9, 2004. Barriers like cement mounds and iron fences are still set up outside many important buildings in case of terror attacks as the "9¡¤11" attack has passed nearly three years. (Xinhua Photo/Lu Mingxiang)

 Two US policemen stand on guard in the street of Washington, Sept. 9, 2004. (Xinhua Photo/Lu Mingxiang)