Right - where do those doors go to?
I thought those doors went to the stables of the Steardan, the quarters for the grooms of the Steardan and a passageway to the rest of the underground fortress (IIRC, there was a hallway running off the top edge of one of the two undergrounds maps and it was that hallway which went to the 'backside' of "the black rectangle at the left of the diagram").
You're right, #78. I don't know how I missed that. I had read the description for long hallway #52 that goes off into nowhere, and somehow missed #78, or assumed it was the same.
#78 says "Corridor. Leading to the great iron gates above the city."
Thanks for all the suggestions, guys. I wanted to know this before running my game on Saturday... the party have just started exploring the fortress.
I'm running a heavily modified version of the Grand Campaign with a bunch of other modules thrown in, and after the long chase through the tunnels by the Doombringer, I had the long tunnel eastward actually join up with the the collapsed tunnel at #76 in the Cloudlords fortress (which is currently abandoned).
Once the party get out, they'll meet up with a Duranaki patrol--the Duranaki keep watch on the fortress to make sure the Cloudlords aren't taking up residence again. So there'll be a bit of a confrontation, and the party will eventually be released with dire warnings not to interfere with Duranaki affairs.
Then we'll pick up the GC trail again, and they'll head to Zener Morndaak's house, with the patrol following behind, unknown to the party. That way, when the party are discovered with the dead Loremaster, the Duranakis' hostile reaction is even more understandable...