Rooftop help

Does anyone what buttons to press to go up to the most top platform, there are 2 ways, 1 way that needs ppl below you and the other you jump by yourself. How do you do the one by yourself to go up? I keep trying to get up there but I can't get on top of it, I see others do it. Help me please/
Edit: I'm talking about the tall ass building, not the place with the bricks.

You can jump twice o-o? @Blake19