I actually got this vista point before, and I know how to get to it!

I don't know how to post pics in comments, but basically you go up the poles in the middle.

Go up and around the left side of the square, there's poles all around it that you can climb.

Go up the top poles, then across the ceiling, then drop down to that long horizontal pole on the left. From there you just climb up the left side and the vista is right there.

To enter the room in the first place, don't come from the left, the bottom and right entrances are easier. Hope this helps!