What was the hardest dungeon you've ever been to in all the Squaresoft games?

For me, i've played FF1(but i'm not done yet, i just got to the earth dungeon-thanks to brian for the walkthrough and lists!), FF8(almost done!), FF9(finally beat it!), and FF10(not 10-2, 10). So far, the hardest one for me has actually been the earth dungeon. The earths have done 89 damage to my thief before. Not fun.