* Castle is a location in the Pokemon Black and White games, not in Pokemon White.
* There is no location in Pokemon White called "Castle". It's likely you're thinking of a different location or game.
Here are some possible locations in Pokemon White where you can get Poke Balls:
* The Pokemon Center: You can buy Poke Balls at the Pokemon Center in any town.
* Early game: You'll often receive Poke Balls as rewards from trainers or for completing certain quests.
* Items: Sometimes Poke Balls can be found in chests, or you might find them laying on the ground in certain areas.
If you remember a specific area where you're trying to find Poke Balls, provide more details, and I can help you find them!