Multiplayer, Switching between maps

All that has played Everquest in wc3 knows that you can move between areas in multiplayer.
My question is how to make that?

They just made the map huge, with tons of different areas. They made it so you cant move the screen past the area your in too.

Is it really that easy? Cause the map feels really huge.

You can't switch different maps on multiplayer... it can be used only on single player campaigns.
The only way is to make a big map and use camera bounds to lock the camera movements to a specific area of a map (that means that you see only the specified area in the minimap)