Colorado Springs is a home rule municipality in, and the county seat of, El Paso County, Colorado, United States. It is the largest city in El Paso County, with a population of 478,961 at the 2020 United States Census, a 15.02% increase since 2010. Colorado Springs is the second-most populous city and the most extensive city in the state of Colorado, and the 40th-most populous city in the United States. It is the principal city of the Colorado Springs metropolitan area and the second-most prominent city of the Front Range Urban Corridor. It is located in east-central Colorado, on Fountain Creek, 70 miles (113 km) south of Denver.
Jiayuguan, known as "the first male pass in the world", is located in the middle of the narrowest valley 5 kilometers west of Jiayuguan City, Gansu Province. the city walls on both sides of the pass cross the Gobi Desert, the suspended Great Wall of Montenegro in the north and the first pier in the south. it is the westernmost pass of the Ming Great Wall. it was once known as Hexi throat in history, because of its dangerous topography and majestic architecture, it is known as the chain key of the border. Jiayuguan is the traffic fortress of the ancient "Silk Road" and one of the three wonders of the Great Wall of China (Shanhaiguan in the east, Zhenbeitai in the middle and Jiayuguan in the west). Jiayuguan was built in the fifth year of Hongwu of the Ming Dynasty (1372). It is composed of inner city, outer city, Luocheng, Wengcheng, trench and the north and south wings of the Great Wall, with a total length of about 60 kilometers. The platform, pier and fortress of the Great Wall are dotted with three lines of defense, namely, the inner city, the outer city and the moat.