地处西北,声名远播的特大型建筑施工企业———中国铁道建筑总公司二十一局集团有限公司,是在近年来我国建筑施工企业中崛起的一支劲旅。该局先后承担了全国铁路具有路网意义的南昆、大秦、陇海、青藏、北疆、南疆等十几条干线铁路建设任务;建成了世界海拔最高的铁路隧道——— Located in the northwest, the famous large-scale construction enterprises --- China Railway Construction Corporation Twenty Bureau Group Co., Ltd., in recent years China’s construction enterprises in the rise of a powerful. The council has assumed the task of railway construction of more than a dozen trunk lines in the Nankan, Daqin, Longhai, Qinghai, Northern and Southern Xinjiang whose national railway network has a road network. The railway tunnel with the highest altitude in the world has been built