From the lower Historic (pix 4, 5, 6, 7) up to Medical Center Way (pic 8), crossing over to the East Ridge Trail and up to the summit (pic 9: a summit flower).
This time from the summit down the North Ridge Trail (pix 10, 11).
I've used this convenient short stairway (pics 12, 13) many times from Medical Center Way to the parking lot so as to descend the wood-railed stairway to its foot, then out to Parnassus. But you can easily just walk downhill to the lot too.
There are around 136 steps from the parking lot down to Medical Center Way behind the hospital buildings. You'll probably see medical personnel ascending and descending this stairway, but it's okay for hikers to use also. I've been doing so for years. Pix 14 through 21.