Mentioned by one of the adventurers rescued from Gerrilad the Grey from the cells off the Ruby Throne Room (maybe Samantha?) when questioned by Axle, Fenpenny, Fernweh, Grexes, and Huzzah!.

Looking at the plateau, it does appear there could be another set of stairs.

Tonk is going to look into it, accompanied by Styx Riviera and [ insert name here ].