Beneath the Marching Tankard (Patreon)
Content
One thing you can trust is that retired adventurers will always add little “somethings” to the businesses they acquire. In the case of the Marching Tankard, Gunter Grohl split the sub-basement into two sections, one cellar accessible from the large basement, and one only accessible by a secret stairwell.
The secret side of the sub-basement includes a small chapel (most likely to one of the patron gods of the Empire, but potentially to one of the gods of chaos if you want Gunter to be part of the problem), and a set of tunnels that lead under the yard of the Marching Tankard and open up via ladders and secret doors into the tack room of the coaching house, and a second that opens up into a small stand of trees outside the walls entirely.
This map (and the maps of the Coaching Inn above it) are available at 1200dpi here: https://dysonlogos.blog/2020/04/11/beneath-the-marching-tankard/