Looking for good open world games

Terraria, when on sale.

First thing that came to my mind from the title was Just Cause 2 and Red Faction Guerilla. But that's the opposite of building stuff. XD

(Haven't actually played Guerilla yet, but finished Armageddon very recently and it was awesome)

Aw, I was about to type out the top open world games, but it seems you are looking for crafting games. :(

I've been playing 7 days to die lately and it has an amazing crafting system and its open world. It has my recommendation.

I just picked up the Rising World game. Shows some promise, you can craft some pretty detailed things.

http://store.steampowered.com/app/324080/

and Medieval Engineers:

http://store.steampowered.com/app/333950/

Both are early access, but that is what it has come down to for me :( I think I have everything else..