I finally reach the top of the fortress where I find not only a bonfire, but a very depressed merchant knight - Ser Sad. Not sure how he gets his wares given you need to "jump" to him, but he has some pretty nice stuff! I also find assistance in the form of Iron Tarkus, a heavy knight who first slays one of the giants who resides up here (the ones I've just been running away from), followed by almost soloing the Iron Golem boss!
Tarkus must be super high level.
Upon its defeat I am swarmed by flying demon things that decide to carry me up the mountain to the edge of Anor Londo. Apparently they also serve as transport back down if I need it, which is a really awkward way to travel. This beautiful place has gigantic sentries watching my every move, but they are nice enough to let me pass if I leave them (and whatever they are guarding) alone.
While it's pretty clear where I'm meant to be headed, I am detoured into a building full of assassin's creed cosplayers with a giant painting I can't interact with. Passed them is the way to the main building but of course the main doors are sealed. I have to go around and fight the same flying demons who were my transport to get through. Ironically, knocking them off a ledge makes them fall to their deaths. Guess I hit them so hard they forgot they could fly?
A number of deaths awaited me just after though, as the narrow path leading towards the building was well defended by a pair of archer knights, who shoot arrows the size of ballista bolts and covered not just my approach but each other. Eventually I was zen enough to blind dodge (via timing) the arrow coming from the back while dealing with the knight in front. One balcony jump later and I found myself in the palace! Woo!