As I was mining for Diamond, I discovered a weird place/cave(?), and there are an already build railway. There is also a box contains an enchanting book, bumpkin seeds, and railways. There is also a wooden construction.
The place is deep, and I haven't explored it all because of the hostile mobs, especially spiders.
Can someone tell me if they encountered such places and what is this place?
Lucky you! I‘m always delighted when I dig down from my very first temporary hut and discover that a mineshaft is below. They provide all the wood I need for the mining excursion and fence posts so I can mine in absolute safety by temporarily fencing off unexplored corridors behind me. Cut the webs with a sword if you want string and I think with shears if you want webs.