How do I reach this Graffiti at the top of Millennium Square?

[An Innocuous Chef]

So I'm at the part where you have to find the Franks in Millennium Square. After talking to him he tells me to go tag a spot on top of a red and orange building, but I have no idea how to get up there. If anyone who has passed this part could help, I would appreciate it.

[Chao]

throwing a comment down incase anyone else finds out

[Mace]

If you go the the back right corner of the map where the half pipe is with the Vents on the back wall you can climb on top of them on to the roof just ride across the roof and youll see some rails you gotta grind after that youll know ur way !.