As writers, we are all readers first (at least the majority of us). Think about the greatest book you have read. Now, ask yourself how well you were able to imagine where the story took place. Even if your entire story is set in the same building, you need to build a world around your characters. For example: you are writing a murder mystery and everyone is locked inside of a building until the suspect is caught. You will still need to plan and describe the rooms where certain events will take place.