Due to the “sinking” effect that is ever-so-common in Corvis, most construction projects on “bare ground” (often the rooftops of sunken structures) begins with the introduction of large steel posts, driven into the soft earth with the assistance of industrial steamjacks (the local masons have a longstanding relationship with the Steamworker’s Union).

Once the piledriving is completed, a two-foot layer of impermeable clay is laid down to seal off the future basement of the new structure. This basement is typically built above “ground level” and thoroughly sealed against water intrusion (even the Cygnaran Public Works Department’s massive pumps are no guarantee against flood damage, after all). Older structures used pitch for this purpose, but some of the high-end construction projects over the past 100 years or so have taken advantages of certain alchemical compounds developed originally for sealing water leaks in steamworks.

Over the centuries, this has resulted in an irregular pattern of impermeable strata at various depths throughout the city, and structures have sunk despite the best efforts of Cygnar’s best and brightest architects and engineers. As the canal system has been built, rebuilt, redirected, and repaired, there have been no less than twenty serviceable tunnels discovered that actually pass beneath the canals, with only minor leakage from above. Criminal elements such as the Gertens Family have made use of such tunnels for years now for use in evading the Watch for smuggling and kidnapping operations.

Entrances to known tunnels of this nature are under observation at all times by a group of operatives for the Crown for use by King Leto’s intelligence network. The Town Watch is officially unaware of their presence, though Captain Helstrom has made beneficial use of them on a number of occasions.