In Final Fantasy IV, you will eventually be able to explore three worlds. There is the Overworld, where most of the story takes place. Then you will find yourself in the Underworld, Dwarves, and Summon Lords. And then finally the Lunar World. Little is known about the Lunar World. However it is clear this is where destinies are born and destroyed.

Over World

1- Baron Kingdom 2- Myst cave 3- Myst Village 4- Kaipo 5- Underground Waterway 6- Damcyan Castle 7- Antlion Cave 8- Mt. Hobs 9- Fabul 10- Mysidia 11- Mount Ordeals	12- Troia Kingdom 13- Chocobo Village 14- Magnetic Cavern 15- Agart 16- Mythril Village 17- Eblan Castle 18- Eblan cave 19- Tower of Babil 20- Chocobo Forest 21- Adamant Grotto