Used to not be allowed in the building,

from Wiz Khalifa (Ft. Curren$y) – Rooftops Lyrics on Rap Genius

Meaning

He’s talking about how he went from the bottom (no one really knowing his name) to the top (being famous and having a lot of money).
Rooftop — – he’s ON TOP
Not even allowed in the building — – he’s NOBODY

To help improve the meaning of these lyrics, visit “Rooftops” by Wiz Khalifa (Ft. Curren$y) Lyrics and leave a comment on the lyrics box