Failed automated baggage system and unused tunnels

DIA was constructed with an automated baggage handling system that experienced repeated mechanical problems, contributing to construction delays and increased costs. The system's failures led to litigation and the decision to abandon significant portions of it, leaving unused tunnels, infrastructure, and equipment in parts of the airport. The presence of these unused subterranean areas and the system's troubled history have been referenced in UFO- and conspiracy-related discussions about the airport.