Where is Cerulean Cave in Pokemon HeartGold and SoulSilver?

Pokemon in Cerulean Cave:

Mewtwo (average/only level 70)

Primape (average level 55)

Ditto (average level 55)

Kadabra (average level 58)

Parasect (average level 56)

Machoke (average level 46)

Slobro (average level 50)

Slopoke (average level 36)

Golbat (average level 48)

Magneton (average level 50)

Wobbafet (average level 58)

Note:Don't use a master ball to catch Mewtwo use a ton of ultra balls because you will want to save the master ball to catch another legendary pokemon. You will find it randomly in a pacth of grass. As soon as you attack, it will try to flee so either have a Wobbafet (I don't know how to reall spell the name) or just use a master ball right of the bat.
It is in the house directly below the Game Corner. Talk to the guy in the back.