Once you defeat the Pontiff Sulyvahn in Irithyll of the Boreal Valley and explored the area you will have two Options either you can explore the Irithyll Dungeon or you can head Up and Explore Anor Londo. Here you will have to face some new kind of Enemies which includes Rotten Flesh of Aldrich, Silver Knight, Giant Slaves and much more. So let’s start with the walkthrough.
Pontiff Sulyvahn Bonfire
Once you have Lit the Water Reserve Bonfire you can head back to the Pontiff Sulyvahn or head outside Kill couple of Giants Slaves then head right towards last the Pillar and head up to take few of More enemies in Purple throwing Flames at you. This is Just For the Loot bases, if you have already taken care of those guys then you are ready to explore the new area which is up of the Castle(Water Reserve Bonfire).
Anor Londo Bonfire
On Top of the Castle head Right and jump down on another platform. Here you need to be quick enough to run on the other side of the Castle as there are Silver Knights with great bows shooting at you. Take left kill those Knights and head down from the other side of the Roof and Enter from the other side of the Castle Entrance. Pull the Lever on the Right to trigger the Bridge mechanics work, once you get on the bridge head up and pull the lever again to go up and Lit the Anor Londo Bonfire.
Prison Tower Bonfire
Get back to the Tower and head down and you will see a Bonfire at the Right-hand side. Keep walking as this is an invisible Bridge and Lit the Bonfire, on your left, you will find Yorshka so talk to her to get Blade of the Dark Moon. Now if you get inside and start Dropping down then you will return back to Church of Yorshka Bonfire.
Fast Travel to Anor Londo Bonfire and head up to the Main Tower where you will encounter two Silver Knights. As you see the door is closed, head left get inside and start climbing upstairs. Make sure you have good Fire armor to take those Purple enemies down then head down and Open the Main Door just to make sure if you die then you can directly enter from the Bonfire.
Aldrich, Devourer of Gods Boss
As you Open the Door you will encounter Deep Accursed who is not that difficult to deal with but just make sure you are not 100% cursed. Now get ready to take down the Main Boss os the Area. Here is the complete detail on how to defeat Aldrich, Devourer of Gods Boss Guide. Thus concluding the Walkthrough for Anor Londor and we can Continue with the Irithyll Dungeon or you can check out our Dark Souls 3 Wiki Page to know more about the game.