Holt is the hub from which the party operates. It contains three shops: Weapons, Armor, and Items, as well as the Dark Assembly, the Hospital, the Item Worlds and a handful of citizens that you can talk to. Throughout the story Holt is temporarily replaced by the Colosseum's waiting room, the passage between the floors of the Colosseum and the Land of Carnage.
See the following pages for in-depth information on each of the palaces features.