It's possible you're thinking of Cianwood City, a key location in the game. Here's how you get there:
1. Beat the Gym Leader in Ecruteak City: This is the fourth Gym, led by Morty who specializes in Ghost-type Pokemon.
2. Travel east: After defeating Morty, head east from Ecruteak City.
3. Follow the path: You'll pass through a forest area and then a cave (the "Whirl Islands"). Continue following the path until you reach Cianwood City.
Key Points:
* Cianwood City is important: This city houses the fifth Gym, led by Chuck who specializes in Fighting-type Pokemon.
* The Whirl Islands are a challenge: The cave leading to Cianwood is a difficult area with multiple trainers and puzzles.
* Preparation is key: Be sure to train your Pokemon and stock up on potions before entering the Whirl Islands.
Let me know if you have any other questions about Pokemon Crystal or other Pokemon games!