From GA-400 going north:

Take Georgia-400 north to exit 10 - Old Milton Parkway.  Turn right (east) on Old Milton Parkway.  Turn left at the third traffic light onto North Point Parkway.  Turn at the first left into the Northside/Alpharetta Medical Campus entrance.

From GA-400 going south:

Take Georgia-400 south to Exit 10 - Old Milton Parkway.  Turn left (east) on Old Milton Parkway.  Turn left at the fourth traffic light onto North Point Parkway.  Turn at the first left into the Northside/Alpharetta Medical Campus entrance.