The Kobolds accessed the Folly from a cave system below. I find that the style of Worldographer is not up to the task and I am looking for an alternative style. It's wonderful for producing battle mats and large scale maps, but not so hot with cave systems.
I'd like the base the system of caves on Carlsbad Caverns. I've been reviewing maps and brochures of the place for weeks. The cavern under the Folly is much smaller than Carlsbad Caverns.
I've also been looking at the art in DMGR1 Campaign Sourcebook and Catacomb Guide. This book is one of my favorite's even though it's technically e2 D&D. At the time of e2's launch, I didn't realize that it was a revamped system and was using willy nilly in my AD&D campaigns. I love the isometic projections in this book and would probably want to copy that style.