short, fairly easy hike but not well labelled/marked!  i went with a friend who had been before so that's how i knew which way to go.  even then, we both got lost trying to find the parking lot!  easy parking in the zoo parking lot - you can see the "hole in the rock" from there so just park on that end of the lot.  just a short walk down a paved road then some light terrain up the hill.  not a hard hike - i did it in flat sandals.  great photo ops at the top!  

we went on a weekday so there were very few people around but my friend says it gets crowded on weekdays.  also, no water fountains and bathrooms in sight so take care of all that before you go!