[Crono]

If you mean the Skill guilds, then yes you can travel to other cities to be part of other guilds, but it's much better to be in a guild that resides in your town.

Also, if you pick a race and pick the right native town, you get a special stat enhancing ring. Example: If you be a Hume or Galka, if you choose Bastok you will get the Bastok ring. If you're an Elvaan and choose San d'Oria, you get the San d'Oria ring, and finally if you pick Tarutaru and Mithra and are from Windurst, you get the Windurst ring.