Pokémon Ruby and Sapphire/Petalburg City

Petalburg City is one of the largest cities found and the first place you'll see a Pokémon Gym.

Houses

 * Wally's House
 * Petalburg Gym
 * Pokémon Center
 * PokéMart

Items

 * Rare Candy - Surf across the patch of water at the top of the city
 * ? - Surf across the patch of water at the bottom of the city
 * HM 03 Surf - Get this from Wally's Uncle after you beat your father in the 5th gym

Events

 * This is where you meet Wally for the first time in your father's gym, which you need to do before you move on. If you try passing through town instead, a citizen will stop you and direct you to the gym.  When you meet Wally in the gym, you will be shown the procedure to capture Pokémon.
 * This is also where you fight your father in the 5th gym, but only after you get the first 4 badges.