C1359 Sewer
Leaning on the wall, Orson used his ears to listen as he knocked on the wall.
"Dong Dong", the sound echoed in the darkness.
"Fortunately, this wall is not that thick, about one to three meters. With our current tools, we should be able to cut through it in three hours. Everyone, let's begin."
The team that Orson led was an archaeological team