A dwarven adventurer started out in Breedblockade, which appears to have no exit. I've found a single stair which goes between the crafting floor & the dormitories.

Historical note: Breedblockade is a dwarven fortress that was founded by a mostly-human group and is now populated mainly by goblins. The last mayor was a human who put the world into the Golden Age only to meet with great personal tragedy when all but one of his nine children were abducted by the goblin civ (the other child was eaten by a forgotten beast as an infant). When his wife, the mayor, died, he succeeded her. When he died of old age, alone & childless, a goblin became mayor.