Earlier quoted context omitted.
A lot of universities have their own power plants, especially of a certain age. The U of M in Ann Arbor has a plant and uses the waste heat to keep the relevant sidewalks free of ice and snow in the winter.
We could always see where the steam tunnel broke from the sidewalk and went into the building because there was a patch of bare grass growing in the heat the steam gave it underground.
The steam tunnels were somewhat notorious for awhile there, played a role in the Dungeons and Dragons chapter of the satanic panic of the 80s.
Still, there were always a couple ways to get in. Fond memories.