It seems like its been said 10x already, but these are exactly like the tunnels under the University of Colorado! I've only explored the not-so-interesting utility maintenance tunnels, which are packed with steam-pipes, cable tv lines etc, but I know there are sections that are very wide open (where you don't have to crouch under pipes). We made it from the engineering center to farrand and even past the planetarium to some dorms (they tend to let you out in the boiler rooms in basement), but never into the main parts of the tunnel system. The tunnels are centered under the heating building and you can peer into them through many grates around campus. I hear in the main sections there are many doors that open in front, but lock behind you (just hope you don't reach a dead end). Also there are plenty of signs warning of asbestos, so not a bad idea to wear a mask =P. Don't get caught or you might get expelled too!