Now once you get to the very top of the fortress and exit the fog gate you finally see who's been throwing the boulders you can either take him out with arrows from where you are at he will just stand there and give you clear shots to his head, or you can run up to him which is harder as he will throw a fit and stomp and punch the ground draining your stamina. BUT if you go down the stairs you can get the Flame Stoneplate Ring which increases your fire defense which you need cause as soon as you go up the first set of stairs another giant at the very very top of the Fortress is gonna throw firebombs at you and they do massive amounts of fire damage. After the second stairs theirs going to be a missing piece of wall on the right side and if you drop down you can find a hidden bonfire which is good just in case you die. So first thing you SHOULD do is go to the very top and kill the giant you can lure him out and then duck into the stairwell until he does his fit attack which will tire him out and giving you some decent hits in and good thing is he won't respawn. He is your top priority if you want to explore and get your items. If you go across the walkway there's going to be a broken piece you can jump over to get to the Crestfallen Merchant who actually sells you some useful things, besides the firebombs and green blossoms he will sell you upgrading materials, arrows, a Balder armor set, a steel armor set, and a Catarina armor set but in my opinion the best things he sells are the Thunder and Magic Stoneplate Rings which like the Fire Stoneplate Ring increases your defense for Lighting by a set 50 and just increases your Magic Defense.
Futher down from where you met the merchant is a snake mage guarding the cage keep which correct me if I'm wrong opens a shortcut in Sen's Fortress and frees Big Hat I'm not sure but i know its for the shortcut as well. There is also a respawning Black Knight where you can farm for titanite shard there is also a ladder to get to a tower holding a Hollowed Prince Ricard who you kill to get his Rapier (Ricard's Rapier) after all that head up to the fog gate and off to the right is a path where you can summon the ALMIGHTY IRON TARKUS all kidding aside Iron Tarkus is pretty amazing as he can tank all of the Iron Golems' attacks and if your lucky he can push him to the edge and get him to fall off but I'm getting ahead of myself lets talk about the Iron Golem...
Once you kill the Iron Golem you will get his soul, some souls, humanity, and a trip to Anor Londo so enjoy those and let me tell you about the Core of the Iron Golem and what you can make with it.
The Golem Axe is one of the weapons you can make from the Core of the Iron Golem to use it requires 36 strength and is a pretty decent weapon to have by this part of Dark Souls and holding it one handed and using the power attack will create an Air Slash the same as the Iron Golem BUT it eats away 50 durability, to make it just upgrade any axe weapon to +10 and use the core at the Giant Blacksmith and there you go.
Next is the Dragon Bone Fist sorry no picture for this one the Dark Souls wiki isn't reliable for pictures but these well I cant really say I have an opinion for these as I never really used a Fist type weapon but it seems to be pretty good you only need 20 strength its one handed strong attack unleashes a powerful uppercut that tosses enemies into the air it strangely boosts your Magic and Fire defense by 30 don't know why but this weapon can be buffed for extra damage don't know if that means you can get the blacksmith to put either magic, chaos, ect. on it or you use the resins on it but if you like using Fist type weapons go with these and to get it you cannot use the Dark Hand sadly but if your part of the Forest Hunters Covenant you can go to Blighttown and see Shiva of the East and by some Claws and other Fist Type weapons as well as the Washing Pole and other Katana weapons if you want to make the Chaos Blade.
Either way enjoy your stuff and I'll put another one up soon.