The Underground Booty Squad
Under all of the neighborhood along W. Seventh bordered by 35E, the river, and downtown, lies a maze of walking-height sewers. By far the system with the highest number of total miles of tunnel. Unfortunately, they're all "sanitary" sewer. In other words, full of crap. The labyrinth is about three miles from end to end. Most of these run underneath streets, but not all streets have sewers underneath them. Finding a way through this maze without hitting sections of tunnel filled with a disgusting, smelly bubble-sucking substance is a challenge, but it is possible to cross the maze using relatively dry tunnels.
-Tunnelcity, 2004