The underground ruins (地下遺跡,Chika iseki?) are located underneath the castle. They are the entrance to the mining areas where the Plaga parasites were being unearthed.
Multiple ruins can be seen inside the underground passage. This path also leads to the mine area.
The underground ruins is guarded by the villagers where they have prepared bear traps around the place. To enter the Trolley mines, Leon Scott Kennedy must find the Key of the mine where he must fight two Chainsaw man and also a huge numbers of villagers. Heading towards the Trolley mines, Leon fell into a trap room with spiky on the ceiling.
"Up ahead rests the offering to the lion"
The locked door
(locked door sound) It's locked. There's gotta be a key around here somewhere.
The door in the trap room while the ceiling is falling