The Library in Halo. Argh, gurr. It was not solved in the way I thought it was supposed to be.
The Cemetery in Sepulcro in Red Dead, Undead Nightmare. It's almost funny, when you look at my times, it's like 3-6 minutes, then like 28 minutes for that cemetery.
And some ice level in Super Mario Galaxy - tried for a while, but gave up and haven't come back to it in years.