There was a pixel-art video recently uploaded by Thorlar, weighing in at 1,128,960 blocks. A million blocks.
Seriously, this thing is huge.
This particular piece has a mix of Diablo art, Kerrigan (SC2), and Deathwing (WoW), and it is unbelievably huge. It's large enough that it can't load normally in-game, taking a number of fly-bys to see at all. However, from above, it is awesomely detailed. The piece claims to be the largest ever made, which could very well be true! Even if it isn't, this is one amazing picture, and definitely worth a look!