So far Blighttown, but not the actual town part. The stupid freaking secret area, that tree hollow thing. Fuck that place. Fuck it to hell. Also the lava area after the spider *****, once you kill Ceaseless Discharge it gets filled up with super tough enemies. I died twice really fast and was like "Nope" so I'm doing londo ruins now. Just drained it.
I also briefely went into the Archives as well as Catacombs. Archives don't seem too bad - tough, but not too bad. Catacombs I was like "wtf" with the skulls and the skeletons that keep raising themselves so I got the hell out. I think I have a blessed weapon now I can use, though. If not I'll wait till I do.