I think I can agree with that....
But why would there be no explanation given?
Looking at the illustrations and the very short descriptions (most are 1-2 words) on the otherwise blank opposite page I can see that you could get that impression, it does make some sense.
I do agree that some of the illustrations give a hint to its location.
And some are obvious;
Like "The Guardian" on page 7.
A monster that guards the cave entrance at the start.
In that sketch you see skies and mountains with some trees in the distant background, just beyond the cave mouth.
That is the only sketch with an above ground setting shown.
And of course the next one too (Page 9), as it is labeled THE ENTRANCE....
The Gold Dragon is also quite easily placed at the end too....
Those all match the large two page sketch that shows those in relation to the rest of the dungeon.
Upon looking more closely at the larger map sketch at the front.
Every full page monster sketch seems to be placed (in smaller detail) on the map sketch.
Some are tough to locate, but it appears that most of them (possibly all) are there.
I think I have even located Neutral Ground.... (pages 40-41)
But some of the rest of the sketches would require some speculation at best.
If this book was intended to be an actual adventure scenario, then the
DM running this one would need to do a LOT of filling in.
In fact all of it.
The more I look at the book the more I like it.....
I think wit some work; it would be a really fun one to do from the looks of it.
What PC Levels do you think they would need to be?
My guess would be a minimum of 6-8 PCs averaging 7th level for old school D&D.