C District can be considered as the old district of Cyber City.
The history here may not truly exist, but the memories of the residents indeed show otherwise.
The old district was originally built several years ago, during the war when the sewers were temporarily transformed into air-raid shelters. After the war, they were rebuilt, but only the main thoroughfares were reconstructed. Some smaller branches and hidden tunnels became gathering places for underground organizations or wandering vagrants.
Of course, An Buchen was well aware of this. She had scouted the area before ultimately choosing the location for her Daoist Mansion. The hidden tunnel was near the main artery of the sewer, an area frequented by patrol robots, hence few people were around.
However, this tunnel led to a deep maze that seemed to house a vast "no-patrol zone," where not a few cybernetic beings lay hidden.