How to get to the third giant in Sen's Fortress in Dark Souls?

There is a respawning giant who is loading the boulders into the system, and there's also a giant throwing exploding balls onto platforms on the top of Sen's Fortress. Somewhere around that area you can see another giant kind of in the back. How the hell do you get to him?

I found no way from looking through all the possible perimeters, and the interior of the Sen's Fortress is pretty linear and can be sprinted through in minutes, if you already know the layout.

If I am thinking of the same giant you are referring to, this is how to get to him...

Starting from the beginning of the fortress, after you get past the gate entrance with the two lizards, you enter the start of the guillotine area, drop down to the left and enter the little entrance way shown in the picture.

Climb the ladder in there to the top and there should be a secret entrance behind an arch. Get through that, climb the ladder behind it and it takes you straight to him.

Here are some pictures to point things out, the pictures follow the order of events I described. So it should be self explanatory to get to the giant, hope it helps out.