Lower Undead Burg is the area you can start exploring once you've beaten the Bell Gargoyles and rang the first bell.
Lower Undead Burg
Now that you've made your way down the ladder, you will encounter the Lower Undead Burg. Head up the stairs on the right to unlock a shortcut to the first bonfire in Undead Burg. Then, head back down and towards the fire. Here, there are 3 dogs to deal with, keep your shield up and attack only after they attack you. In addition to this is a hidden path, go right and right again. Here you will find a few fire hollows and a Twin Humanities item.
Now, start to head back to where you fought the dogs. You will hear a voice coming from a door- unlock it with the Residence Key. Here you will find the Sorcerer Griggs of Vinheim, who will return to Firelink Shrine and is able to teach you spells.
Now, push on down the path. You will hear doors open, and three Ninjas will come out. Retreat back, and you will be able to take them out. Beware of their bleed damage, as it can cause significant health loss. Check out he newly open door on the right to get a Mail Breaker.
Push downwards, and there will be 3 Ninjas and a Dog. Deal with the dog first, then draw your attention to the Ninjas, we recommend a strong stunlock weapon like the Claymore or Zweihander to deal with them all in one swoop.
Go forward, and another dog will pop out, deal with this and head into the second door on the right to get the Black Armour set, which is very good for poison resistance. You will see a fog gate in front of you, which will lead to another boss- the infamous Capra Demon boss.
After killing the Capra Demon, head back out of the boss arena and hang a left down some stairs. After heading down, you will encounter more Ninjas. One is directly to the left, and another just ahead. Take these out and push onwards.
If you're looking for more help, our Dark Souls walkthrough and guide can help with all other areas of the game, including the dreadedTaurus Demon, Capra Demon, Ornstein and Smough bosses. Meanwhile, we have explainers on how to access DLC Artorias of the Abyss, the best gift and best class in Dark Souls, Dark Souls' best weapons, Dark Souls Covenants, Dark Souls Estus Flasks locations, Dark Souls Titanite Slab locations and NPC quests including Lautrec of Carim.
Lower Undead Burg continued
At the end of this corridor, you will find a Large Soul of Lost Undead. Then head up and towards the staircase and enter. Head up, kill the Archer, and then head up another level where you will see a doorway.
To the right is another Merchant, and if you follow the path, you will unlock a gate, which leads back to Firelink Shrine and where you first entered the Undead Burg. Visit Firelink Shrine, if you so wish, upgrade your weapons, and after you're all done here, head back to the merchant and get out of the building.
Head outside and down the stairs to a closed door. Unlock this door, using the Key to the Depths. Head inside and downstairs, from here, you will reach The Depths.
Be sure you're fully prepared for this foray into the sewers. Use all of the shortcuts and Souls you have attained in order to prepare. Now, head down the stairs and towards the Depths, which is optional, but do this in order to ensure you're heading through areas which correctly scale to your level.
You can get to the Second Bell very easily, if you picked the Master Key. If you want to skip The Depths, you can head straight into Blighttown by going to New Londo Ruins, passing through the Valley of Drakes and into Blighttown.
However, if you do not wish to sequence break here, head down into The Depths.