If you've been to the Undead settlement then you already know this. In the Undead Settlement at the Foot of the High Wall, there's a place with a bunch of dead pilgrims, except for that one sorcerer guy. Anyway, if you peer over the edge you can see a broken bridge that has a dead dragon and a few loot gleams. I was wondering how to get over there.
This bridge is accessible from Farron Keep. This is location where you fight mini boss:
It's not hard to find: in swamp area look for huge ladder, climb it, there will be room with bonfire, use elevator next to it, then search for a gap in railing.
On this map ladder is marked as B, I put map as spoiler just in case:
This walkhthrough video can show exact path.