Goldenrod City is the largest city in the Johto Region, and contains the location of the third Gym. It is the third biggest city in the Pokémon World, and is also known as the place where Bill's family lives. Despite its size, it lacks any extraordinary importance other than containing the 3rd Gym Leader Whitney and, in Generation IV, being home to the Global Terminal. Later in the storyline the Radio Tower is taken over by Team Rocket.
It also has a Magnet Train which connects Johto and Kanto, which starts in Goldenrod and ends in Saffron City. There is a Bike Shop here where you can get a Bicycle for free. The Goldenrod Department Store is the largest store within Johto. Near the entrance to Route 35, is the Name Rater's house. There are two entrances to the Goldenrod Tunnel here.
The Gym Leader of Goldenrod City is Whitney and she uses Normal-type Pokémon. After you defeat her, she will give you the Plain Badge and TM45 (Attract).