The inside of The Celestial Voyager varies depending on where exactly you are on this giant ship... But to keep it simple we talk about the city plaza (the largest place within this ship and also the most common).
Within the city plaza you will find almost everything: from all kinds of stores to restaurant and cafes to even nature points. the options are almost endless!
There are also transportation pods (sort of like trains) within the city that can easily transport you from one point to another with that no spaceships are allowed to fly here.