Anor Londo is an area that is late in Dark Souls III. The legendary city that once housed gods is now ruled and twisted by Aldrich, Devour of Gods. That alone should tell you that this is not a friendly place, even by Dark Souls’ standards.
Anor Londo follows the Irithyll of the Boreal Valley area, and cannot be accessed until you defeat Pontiff Slyvahn. This opens up the way for you to exit this area and progress in Dark Souls III. After defeating the boss, head up the stairs where you’ll find two Crystal Lizards, then head up the stairs to your left. Here is where things start to get difficult. To your right will be an open area with giants and Deacons, head left to find a staircase leading to the Deacons.
If you happen to have an Ember that is activated you will be invaded by two AI opponents who are fast and powerful, but don’t have a lot of health. Aldrich Faithful Talib and Aldrich Faithful Jesus will appear once you head towards the end of the area with the Deacons (who you should be killing as you move on). They use magic and ranged attacks, so be careful. One actually appears before the other, so you can use this to lure it towards you far away so you can fight one on one.