Denver International Airport — Denver, United States

Land area sets DEN apart immediately: its footprint ranks among the largest of any airport on the planet, sprawling across acreage far exceeding Manhattan Island and sitting a considerable drive from downtown Denver. The terminal's distinctive peaked white roof, evoking the nearby Rocky Mountains or a row of tents, has become one of the most recognizable pieces of airport architecture in the country since the facility opened in 1995, replacing the older, more central Stapleton Airport. United Airlines and Frontier Airlines both run substantial hub networks from Denver, exploiting its central location for coast-to-coast connecting traffic. The airport has also attracted an outsized share of internet conspiracy theories over the years, involving its public art and rumored underground facilities, adding odd pop-culture notoriety to an otherwise conventional major hub.