Walldriving Stunt #12 - Top of the building
First, perform Stunt 1 to get behind the freeway wall. Then drive north. Look for a long building with big chimneys on top of it.
Keep driving north until you get to the water, turn around and drive back south towards the building with the chimneys. At the end of it start walldriving.
It's a difficult stunt, most of the times it goes wrong but sometimes you land on top of the building.