how do you get up on the really tall building

hey you can use jetpacks to reach at the top of the building. Hey why don't you try a jet plane and fly it so high and jump from it, its so much fun. when you reach closer to ground then release your parachute. You'll land safely.. It is much more fun when you are being chased by police force and even more fun when being chased by armies and jet planes. whew enjoy the game

In one of the missions you can take a window washers lift to the top of a building. I haven't seen one just running around, but you might find one.

They probably used a helicopter. Some of the tall buildings have doors you can enter and be instantly transported to top, but most you need to use heli. Dan