At 5,431 feet above sea level and covering more than 54 square miles, the Denver International Airport is a hub for westward-bound mountaineers, college students and stewardesses — the largest airport in the United States and the second largest in the world.

In part because of its size, DIA is also home to a swarm of conspiracy theories concerning the structure of the building and the eerie statues and paintings that greet travelers. Some visitors attribute the two-year delay in construction that put the structure $3.1 billion over budget to the secret construction of  a government bunker or underground military facility below the hundreds of thousands of speed-walking feet and rolling suitcases.

Though evidence of government conspiracy with the airport’s designers remains speculative at best, the artwork commissioned for the airport can support their claims. The 32-foot-tall Blue Mustang, a rearing fiberglass horse with glowing red eyes, greets visitors outside on the roadway to the terminals. The statue itself has been shrouded in superstition since its installation in 2008, two years after a portion of the 9,000-pound statue pinned its sculptor Luis Jiménez to a steel support, killing him. While supporters have heralded the big blue horse as an brave alternative to the soothing “visual Dramamine” that characterizes other airport art, opponents to the statue have done everything from nicknaming it “Blucifer” and “Satan’s Steed,” even taking to Facebook to air their displeasure (the group’s name is “DIA’s heinous blue mustang has got to go”).  At their most extreme, opponents have identified the statue as an apocalyptic symbol, linking it to the speculation of underground facilities and government conspiracies, citing verses from the Book of Revelations about the four horses of the apocalypse.

This apocalyptic take on the art continues with the murals of Mexican-American artist Leo Tanguma outside the airport. Some viewers have interpreted the imagery of fire and smoke, as well as the military figures depicted above sleeping children, as symbols in a subversive message of violence, rather than the struggle for liberation and democracy, as the artist said he intended.

There’s no telling how a given visitor will respond to Tanguma’s murals or to the Blue Mustang, and proof is yet to be seen of secret chambers miles beneath the cafés and runways at the Denver International Airport. But it’s clear that for some travelers, the cloud of conspiracy that surrounds the DIA will occupy them longer than that four-hour delay to Moab.