The Sophie Vasi's underground city was like a labyrinth that was full of bends and hidden traps. If one were not familiar with the layout of the underground levels and strayed into it, the activation of the hidden traps would cause them to become easily lost.
The underground city was divided into four sections: north, south, east, and west. A massive drug lab which did both research and production occupied the northern and western sides whilst the eastern and southern sides were storage areas for sundries.
As there were too many people at the headquarters, An Xunuo was forced to escape toward the southern side.