Tales from the Outer Darkness
After a generation something was able to open a path that was under the north tower, a set of stairs leading in to the underground tunnels of the Cathedral. In time, local adventures sought to find the lost treasures and powers of the dead. The gloom that holds here is enough to hide whatever secrets from the eyes of the living.
It is thought that these excursions keep the evil at bay, and brings some wealth to the local town in the process. That many do not return from these excursions just shows the danger the ruins still possess and the need for armed parties to keep the evil at bay, or at least happy.
Here is a listing of some of the beasts within.