A short but eventful (and lucrative) trek to unlock the boss arena in Undead Settlement.
Dark Souls 3: Dilapidated Bridge to Rotted Greatwood
Start at the Dilapidated Bridge bonfire and take the path we haven’t explored yet - past the patrolling woodsman and through the gate towards the tree. Assuming you've done everything we've suggested so far, you'll be relatively safe on what was once a very hazardous route.
Advance slowly along the path and do not get close to enemies; you’ll see why shortly if you don't already know. When all the baddies are clear – including the pack that advances towards you as you approach the building at the end – you can collect an Ember, a Large Soul of a Deserted Corpse, several Young White Branches and a Reinforced Club from around the tree, plus whatever the dead enemies drop. If you feel brave, dash and jump to the broken section of path to grab an Undead Bone Shard. Burn this at the bonfire in Firelink Shrine to increase Estus recovery.
Before entering the building at the end of the path, double back up the tree-lined hillside through the cemetery. There’s a wooden shack on the right side (facing back towards Dilapidated Bridge) with an item glow. You’ll be ambushed by an assassin with a sword as you approach. The glow contains a full set of Cleric gear and a Blue Wooden Shield. A little further into this area you can grab the Mortician’s Ashes. Take these back the Shrine Handmaid at Firelink Shrine to unlock new items for sale. More on that later.
Head towards the building now. A red-eyed enemy stands up as you approach the door. Don’t fancy the fight? Stand as far back as you can and aggro him with an arrow, then sprint away. Your pal the giant does the rest, if you’re lucky.
Back inside the building, climb the stairs then turn around and look behind you. Dash jump to the broken floorboards and walk out onto the little balcony to grab a Great Scythe.
Continue along the path and through the old church. Make sure you open the big doors on your right at the end of the corridor for an easy shortcut back to this boss arena from nearby bonfires. It’s boss time now.