The world's largest steam engine is coming back to Colorado. Union Pacific will bring Big Boy No. 4014 through Colorado from Monday, Oct. 21, to Wednesday, Oct. 23, on its "Heartland of America Tour." The fall tour, which began in August, has the famed locomotive traveling from its open in Cheyenne, Wyoming, through nine states, including Colorado. See the schedule at the link in our bio. #bigboy4014 #unionpacific #cheyenne #denver #unionstation #trains #locomotive