by Sentiel Mon Dec 17, 2012 5:52 am
It's just like the area behind Iron Golem. You can see something that was clearly supposed to be a path and when you climb the bell tower and look with binoculars in that direction, you can see that the wall isn't there and you can see inside. There's something resembling a stairs, leading upwards, probably to Anor Londo.
Similar things are in Daughter of Chaos area (where you find Kirk's gear) and in Centipede Demon area. They all look like passages, that were blocked, but not by a rubble, or landslide, but just a wall, which, at least to me, seems like they were supposed to lead somewhere, but got blocked, perhaps devs didn't have enough time.
The city below Firelink Shrine is probably the same, as there would be no reason to put it there if you couldn't go there. Especially with the game's logic of "whatever you can see, you can venture to". You can see Archives from Parish and you can go there, you can go almost anywhere that is connected by land in the whole game.