One small cliff has collapsed recently near the east wall. Some near walls with suspended construction are now showed as "blackness" tiles though they are still accessible with [k] and [q].

Save and world generated in 40.20, save moved to 40.21, then 40.23. No mods. No other fortresses or adventurers retired in this world.

Linked reports

• 0008716: Walls with suspended construction get invisible after cave in