What the trafficking tunnels systems look like and how they're connected

"Tunnels" is kind of a misnomer. It's more like a series of interconnected underground buildings with various levels of sophistication and depth. In this video I'm describing the tunnels directly underneath the aboveground; I will have to talk about the huge underground replica cities (built in giant caverns with a ceiling that looks like the sky but gray) in another. I'm pretty sure those are located extremely far underground but I'm not sure. All I know is that it's another level of depth.