I found this in my bookmarks, I use to research it like crazy.... its very interesting to read..... my Uncle has a high position security job there and told me it does go underground.. but no one is allowed below the 2nd floor..... he also thinks there are underground highways leading to other military bases......... I've been there this summer and seen the pictures, they r freakin weird......
http://www.anomalies-unlimited.com/Denver_Airport.html