When space is narrow and limited (such as in condos, small homes, and apartments), the corridor or galley-style layout is often the only kind of design possible. In this design, two walls facing each other have all of the kitchen services. A galley kitchen may be open on both the remaining sides, allowing the kitchen to also serve as a passageway between spaces. Or, one of the two remaining walls can contain a window or exterior door, or it may be simply walled off.