A building layout with a square core mass and four equal limbs. The limbs are made up of blocks of space that are either one room or multiple rooms. Each block has an exterior wall to itself, providing privacy for its occupants. A cross-shaped passage runs through each block from front to back. This allows light and air to flow through the building even on the darkest days and coolest nights. The Greek Cross plan was very popular in the early 20th century, but it is making a comeback now. Its unique shape is appealing, and it can be easily customized by changing the size of the blocks and the number of floors. It is also easy to maintain because there are no moving parts inside the house - just clean the windows regularly. The Greek Cross plan is based on a central square or "cross" section of space, which is surrounded by identical rooms on all sides. The rooms open onto the cross-shaped hallways that lead from one side of the building to the other. These corridors run almost the entire length of the building, connecting the rooms on different levels. At the center of each floor is a stairway going down into the square hole where the staircase and elevator would normally go.