In San Francisco they are used to shackle sex slaves, unisex.
Wouldn't surprise me! I'm not kidding about the Jersey house, it really had iron up there to secure people to their beds, and the third floor wasn't high enough to stand up in. I forget where exactly but it was somewhere in North Jersey. The realtor said they probably used it for indentured servants as well as slaves in colonial times. The windows were just like DiFi's 3rd floor. :)