Live flights at Denver International Airport (DEN)

Denver International Airport opened on February 28, 1995, replacing the landlocked Stapleton airport as the first major new US airport in two decades, and none has been built since. Constructed on 53 square miles of prairie northeast of the city, an area larger than Manhattan and second in the world only to Saudi Arabia's King Fahd airport, it became instantly recognizable for its white tensile-fabric roof evoking the snowcapped Rockies and Native American tipis.

The opening was a saga: an automated baggage system so ambitious it mangled luggage in demonstrations delayed the debut by 16 months and became a business-school case study before being abandoned entirely in 2005. The airport's murals, gargoyle statues, and the rearing blue mustang sculpture nicknamed "Blucifer," which killed its own sculptor when a section fell on him, have fed a cottage industry of conspiracy theories that the airport cheerfully mocks in its own marketing.

Operationally the gamble paid off. In 2003 runway 16R/34L opened as North America's longest commercial runway at 16,000 feet, and Denver grew into a three-hub airport for United, Southwest, and Frontier, ranking in recent years among the world's five busiest airports with more than 75 million passengers.

Denver operates six runways, four north-south and two east-west, spread across a site so large that further expansion to a dozen runways remains possible, with the 16,000-foot 16R/34L handling heavy departures in thin mile-high air. Jeppesen Terminal's fabric peaks front three widely spaced midfield concourses, A, B, and C, linked by an underground train, with recent gate expansions pushing capacity past 100 million.

United runs one of its largest hubs on Concourse B, Southwest builds schedules on C, and hometown Frontier adds ultra-low-cost volume. Afternoon thunderstorms and winter snow shape operations, countered by one of the world's largest deicing programs.