The Pewter Museum is located in the far north of Pewter City. It will cost you 50 Pokémon Dollars to get into the guest part of the museum. On the other side (which is known as the "employees only" side), you can receive an Old Amber fossil from the scientist, but the only way to get to that side is use Cut on a small tree.
In Generation II, the museum is closed for renovations.
In Generation IV, the museum was open, but only reduced to minor exhibits and one room. Fossils could also be revived here.
The Pewter City Gym is located on the west side of the city. The Gym leader is Brock and he uses Rock Pokémon; after being defeated, he will give the player character the Badge and the player character will be free to leave the city.