The so-called 'Grand Manor of the People' is a sizeable series of cavernous galleries, each with numerous alcoves, offshoots, cracks, and passageways. One of the few places even the most ignorant of Isarn's citizens knows about, La Grande Manoir is home to one of the largest permanent underground populations in Isarn, second only to Les Galeries under the Industrial District. Its inhabitants are primarily those new to the city who are not as fearful of the possibility of a cave-in.
Grande Manoir des Citoyens as an origin / destination is considered 'Public'. It exits to the surface outside of the city walls, but that exit is a large and direct tunnel; you cannot get lost traveling between that entrance and La Grande Manoir.