How to go about making a huge game world

I’m starting the development of a huge (In terms of world size) open-game RPG, and I want to know the best way of going about it. A gigantic terrain won’t work, since I’m using a specified terrain generator and want multiple “biomes,” but multiple terrains wouldn’t really be line-up-able, if you know what I mean. How have others gone about this?

I’m building a huge word too.

I wrote my own MeshTerrain(which contains almost all functions of Terrain) and the Manager as a plugin.

Now I can montage a huge world by multi small meshes, and load/edit them as i need.

This is the best way in my mind.

Mmm . . . I have no idea how to go about this. Help please? I’m a new indie developer. And by new, I mean very new.