Mysterious airport tunnels to open beneath hub long tied to conspiracy theories

Denver International Airport’s mysterious underground tunnels are set to become more visible as officials outline plans to open portions of them. Late Friday, a Frontier Airlines plane struck and killed a person who jumped a fence and ran onto the runway, causing an engine fire and prompting the evacuation of 231 passengers. The accident underscores the airport’s unusual reputation as work continues. Officials announced plans to convert sections of the underground baggage tunnels into pedestrian walkways connecting concourses A, B and C, creating an alternative route for travelers between terminals. The existing underground train system will remain, but pedestrian access will expand. Vision 100 expansion will drive the pedestrian corridors through DIA, aiming to accommodate future growth. Construction is planned to begin in 2027, with an estimated cost of $300 million to $700 million. Funding will come from airport revenue, not taxpayers, according to DIA CEO Phil Washington. Mayor Mike Johnston noted the airport’s unusual reputation and said the new walkways could invite travelers to judge the tunnels for themselves. The project follows years of upgrades and highlights how DIA expands access to spaces long linked with its lore, including the blue horse sculpture.