Question

foe some reason I can't find it.

Answer 1

Pewter City (Japanese: ニビシティ Nibi City) is a city located in northwest Kanto. The locale lies between Viridian Forest (via Route 2) and Mt. Moon (via Route 3). The most notable resident of the city is Brock, the Pewter City Gym Leader. - Bulbapedia

Source

Answer 2

To get there , you have to wake up the snorlax right side of vermilion city using the flute in the radio and go through the diglett cave.
http://pokemondb.net/pokebase/104538/how-you-poke-flute-music-the-radio-wake-snorlax-digletts-cave
This is how you get the flute in the radio