Your message/question is a bit vague.
Always consider that people won't have necessary played the game you're referring to.
So what are you expecting to happen when the player "enters a building" ?
Do you want to take him to another screen ? Do you want some kind of window to appear on top of the current world in which actions can be taken ?
Please be more specific.
On top of my head though, probably having a new layout and using the system action "Go to layout" could be a solution. But it will depend on great part about what you're trying to achieve.