The Town Hall Style Panel is a room inside the Town Hall where you can select the type of hall you like. These styles have to be unlocked by finding an object that can be used to customize the Town Hall. This room is unlocked when you find at least one object that can be used to customize the Town Hall.
There are 9 styles total, including the main one. They are: Jumping Castle, Evil Mastermind, Angelic Idol, Crime Lord, Fairy Princess, Envious, Diggy Dwarf, and Rainbow Brite.