You grab onto a small pipe running along the tunnel wall, and shimmy along it over the hole. You almost lose your grip a few times and your arms burn, but you make it across safely. You forge further into the jungle.
You enter a large chamber carpeted almost entirely by a white-ish moss. Various pipes and platforms peek out from the moss. The ceiling is far above you, and you can see pinpricks of sunlight from grates. There is a raised section along the edge of the chamber, with no moss on it. In the center of the chamber, you see a tall tower-like structure on a raised platform, which has no moss on it either. This is the first building you've seen in the abandoned tunnels.