What language was Diablo written in?

I really love Diablo (the first one, the second ruined the franchise but getting rid of the atmosphere and making it about collecting items as currency) and want to know what language it was written in. Also, I'm currently playing on US East if anyone wants to play with me.

I really wish Blizzard would fix the fucking hacking though. It should take them a single engineer to do it at this point.

First Diablo had much better palette selection, due to 256-colors. Artists post-processed everything manually. The second game had blatant 3d-render with some objects looking out of place, and they were colored using multitexture-like crap.