The chain
In game terms the chain requires a DC 15 Climb check, so Owen was able to do it by just "taking 10". People with a Climb modifier of +4 or under would not be able to it, which means that it would be a bit more risky.
There are no handholds to tie a rope to at the top of the chain, other than the chain itself, which hangs about four feet from the lip of the upper hallway.