>>2647318Most old cities have some sort of underground infrastructure, sounds like this might be more expansive than most. More frequented areas get pretty "sanitized" in terms of where you can access and considering the city wants to start doing tours the easily accessible tunnels are probably quite tame.
With the exception of single entrance mines it's really hard to seal a tunnel in a way that makes it inaccessible since only a single point of entry needs to exist. Find where local drainers (storm drain urbex) hang out online and see what areas/entrances they're talking about, they'd be all over shit like this.
