That is beautiful. Back from the days when plumbing was built to last. Wish my house had such a nice soil and vent pipe.
I bet the gasket on that inspection/rodding eye is a greased felt material, and I bet those bolts will still unscrew after all those years (if you use a ring spanner and some care). The wall of that cast-iron pipe is probably half an inch thick, deadens the sound of running water and will continue to give good service until it rusts through in another 5o years or so.
The plastic pipes inserted into it are probably a recent modification (defacement).
As others have said, if that is your bathroom, the pipe will be needed somewhere. You could put a new one in, but you can't do without one, assuming you want a flush toilet.