Wow... You're right, disturbing. But good. Really good. I liked your description and your imagery. Really nice.
I love the last three lines:
"Unseen
Unheard
Forgotten"
They really make the rest of the poem sink in, in all of its horror.
Wow.. Sad, but amazing.

Eerie!

The flow of images reminded me of some type of horror movie trailer. ;P 'The clinking of chains resounds/in this darkened chamber' is a great picture.

For me, the sentence 'I fall to the ground crushed under their weight' breaks the flow a little. Maybe 'I'm crushed to the ground by their weight' or something along those lines would read better.

You got me wondering about the story behind this poem, and I like that.