The world is divided into "zones", each one of which defines a certain area and has its own unique feel. Some equipment can only be found in certain zones, while other comes from the "global equipment table". In the world of the Last Outpost, there are "outdoor" and "indoor" zones, with many large connecting zones. If you've ever played "Ultima" or another "map with dungeons" style game, it's very similar.
The zones are listed below in the rough order of the difficulty of the hardest mob in the zone. However, some zones have much smaller mobs and are appropriate for adventuring by players significantly smaller than the order might imply. For example, The Haunted Manor has some very difficult mobs, but a level 5 player could actually start to explore and find many worthy targets.