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

Philadelphia is the largest city in the Commonwealth of Pennsylvania, the fifth-most-populous city in the United States, and the core of the sixth-largest metropolitan area in the country. Wikipedia