Bognar's Cellar is found beneath Bognar Felaberk's residence at 1, Acorn Street. Entry requires Bognar's key. A door on the far side of the cellar leads down to the Sewers.

Spoiler: The cellar is inspected during the Uncover the Dhorn Spies quest.
Note: The inner door leading to the sewers will be locked if the Princess did not overhear the conversation between the two mysterious figures on her way through the sewers to the Family's Hideout during Lesson 3. This is controlled using the "Sewertalk" integer variable, with a value of 1 determining if the door should open.
Community content is available under CC-BY-SA unless otherwise noted.