American Express's Denver Centurion Lounge. Thomas Pallini/Insider American Express debuted its 14th Centurion Lounge at Denver International Airport in February. The more than 14,000 square foot lounge is the second-largest in the Centurion Lounge network. Eligible patrons can use the lounge's two bars, dining area, and game room and not have to spend a dime. Visit the Business section of Insider for more stories. American Express opened a new Centurion Lounge at Denver International Airport in February, the latest in the financial services company's growing network of 14 airport lounges that will soon include locations in London and Washington, DC.