My default assumption for old school dungeons is that you’ve come across the ruins of something huge and underground – something like the ruined cities of the Elderlings buried in the swamps in the Rain Wilds stories by Robin Hobb. It’s the basis I use for all my “random dungeon” rolling.
Here is a small dungeon level set up exactly along those premises – the ruins under Axehead Mound have two entrances – one a collapsed wall section that leads into a chamber, the other a pair of ruin-cluttered stairs that lead into the ruins from a ruined above-ground building.
The ruins under Axehead Mound were drawn in a single draft (trying to get back out of the habit of doing pencil roughs first) using a Sakura Micron 03 and 01 pens. If you like it, consider checking out my Patreon campaign where patrons support the creation and release of more free maps like this one.