I've had this idea kicking around my head (and my blog) for several years of a horror-themed dungeon populated by feuding, Machiavellian wizards and sorcerers beneath the foreboding and barren moors. If you're familar with some of the BX classics, it idea draws inspiration from Castle Amber and The Principalities of Glantri, two of my all time favorites from the 80's, along with literary inspirations like Poe, and Lovecraft. (I finished a Master's program last year, so this year it's back to serious gaming).
You might think something like LOTFP would be ideal, but I actually think the content in ACKS on modeling magical research, libraries, experimentation, and undeath, provides a better framework for figuring out what all these evil wizards and warlocks are doing down there in the depths - why they need monster parts from distant places, and rare books and reagents. Although the milieu is ostensibly Elizabethan England, it's a near-Earth version where portals to faerie still exist, and monsters lurk in the dark corners of the world.
Practically speaking, how would you go about creating 16th century England as ACKS domains? There are probably population estimates for 16th century London (either online or cleverly contained in books), and maybe they exist for the broader countryside, too. Starting with population could be a bottoms up approach. I'm sure there are maps of classic English counties, and you could treat each one as an Earldom(?), and go from there (kind of top down). Historical accuracy is less important than a gameable interepretation.
Anyway, I'm about to start research and the thinking part, and figured I'd check in to see if anyone has done a similar project or has suggestions on moving forward.