C123 There's a Cave Here

There's a cave here

He only felt that there was no danger, but he did not know what was deeper inside the cave. With such a large hole, it didn't look like it was formed naturally. This was because the cave entrance was right beside the platform, and the sides of the cave were filled with rocks. This was obviously man-made. Who did it?

Zhou Ann decided to go into the cave to have a look