Enlisted personnel are identified by way of their various 'E' grades ranging from E-1 to E-9. For those service branches recognizing a Warrant Officer rank, 'W' grades range from W-1 to W-5. Likewise Officers are scaled from O-1 to O-10.
China has quite a collection of natural bridges, including one that experts say has the longest span of any natural bridge in the world. The Fairy Bridge (Xianren Qiao), in southwestern China's Guangxi Zhuang Autonomous Region near the border with Vietnam, has a 400-foot span.
Thames Tunnel The oldest underwater tunnel in the world. (0.4 km) (1825 - 1843). Severn Tunnel One of the oldest underwater tunnels in the world (3.62 km) (1873 - 1886). Chesapeake Bay Bridge Tunnel (23 miles (37 km)), connecting Virginia Beach with the Eastern Shore of Virginia (1960 - 1964).