Guadosalam is the homeworld of the Guado race, which includes Maester Seymour, Jyscal, and Tromell Guado. The city is located in an underground, cavern-like structure that has multiple levels (and can be somewhat difficult to navigate). You can access the Farplane from there.

The story takes you through Guadosalam and the Farplane only once. It is the area that the team reaches after crossing the Moonflow and just before they reach the Thunder Plains. Check out the strategy guide and walkthrough section for additional details: