Which is right?
A theme park bases its attractions (with/under/around) a theme, such as Disneyland, which has Disney characters as a theme.With explanation, please.

Question

Answer

"bases it around a theme" would work, and so would "bases it on a theme of..."  In English, we also say " bases it upon a theme" (more formal).  I am not sure why these terms are used:  they are abstract concepts.  Maybe someone with a better grasp of grammar will have a better explanation :)