The Castle, The Ruined Tower, and the Dark Secret

A castle built into the side of a mountain, perhaps an aging king, or an eccentric wizard or alchemist lives here. There is an old ruined tower. The castle has been having problems, and they seem to have started happening since strange shadowy figures started moving in and out of the large tower ruins area.There's a "hidden" hole down into a subterranean network leading to a cavernous thieves hideaway. Are the thieves looting the castle on a regular basis?Deeper past the thieves hideaway hides an even darker secret. A place the thieves fear to tread. It appears there's a darker hole down into The Underdark which has an underground river leading to a dark, dank, cold lair that hosts what horror unfathomable?I've hidden each and every part, so enjoy revealing this large board to your players as they discover them!Fill it in with your own encounters and "end boss". All the above are suggestions!I used these slabs to create this, credit is due their creators:Nox Novahttps://talestavern.com/slab/st-elias-forts-ruins-game-board/Scarnorhttps://talestavern.com/slab/mini-sewer/Ulfhedinnhttps://talestavern.com/slab/quarrys-snare-hideout/Verin 뚱냥이whttps://talestavern.com/slab/underdark-river/toolbearhttps://talestavern.com/slab/dk-cavern-lair-01/