If you're ever in Griffith Park, do me a favor, light up a cigarette (only if you smoke) and put one on James mouth and let him take a couple of puffs, James is a bust of James Dean and everytime I go up there its a tradition and I give him a smoke. This is the observatory featured in his film "Rebel Without a Cause".
This place is a favorite of mine. You get a great view of Los Angeles, especially at night, if get a chance, check out the Planetarium, they also used to have a really cool laser show called "Laserium". I dont know if they still have it but call to check. If you feel fit to do it, you can go hiking here too. They have trails to Mt. Hollywood where the observatory is located.
When you enter the building, you will see the Pendulum, it is very interesting, observe it for a moment, The pendulum demonstrates that the earth rotates, The 240-lb brass ball, which hangs by a wire 40 feet long, swings in a constant direction while the earth turns beneath it.
The best of all Hollywood, we left it for Sunday and we visited in our little tour around with Hans, Lori and Sharon. From here on a clear day, you can have great views of Los Angeles and the Hollywood sign.
The park seems very busy, but we did not had time to explore it :( The summer of 2004, the observatory and the car park was under renovations so it was difficult to park and we could not see the observatory