Hardest Level In a Mario Game?

[Doodle]

What do you think is the hardest level in a Mario game?
Mine is probably 8-3 in SMB or D-4 in SMB:The Lost Levels.

8-3 had so many Hammer Bros. Plus if I made it passed everything, I would screw myself over at those small, spaced out steps before the flagpole. :(

D-4 was the final castle in the game, so it's to be expected. D:

[Nayrman]

8-3 in Mario 2 (Lost Levels)


That level was freaking hard...