Boulder is the county seat and most populous city of Boulder County and the 11th most populous city in the U.S. state of Colorado. Boulder is located at the base of the foothills of the Rocky Mountains at an elevation of 5,430 feet. The city is 25 miles northwest of Denver. Wikipedia

Qidong is a county-level city under the administration of Nantong, Jiangsu province, China. It is located on the north side of the Yangtze River opposite Shanghai and contains the province's easternmost point. It has a population of 1.12 million. The center of the city is named Huilong Township. Wikipedia