Underground tunnels made to deliver heat (in the form of steam) from a central heating plant to multiple buildings. Commonly found on college campuses. Often retrofitted with wires to deliver electricity or telecommunications. Sometimes used by students or other adventurers for recreational purposes, see urban exploration.
We found an open hatch that led into the steam tunnels, and spent a few hours exploring the campus from underground.
by Professor Slats September 18, 2008