well this was the right place.. but anyway. revert to DX9 for this. it will get all the right sides, then make the cubemap static, then you can go back to using DX11.
The info on the top right of the viewport should already show it. Depending on what version you're using, there's a button on the top right(I think it's an I) to toggle it.
some things that are unclear to me -is there an entrance on the right bottom corner ? i looks like it -whats with the pillar on the right ? it doesnt really make much sense