An elevation is a view of a 3D form when viewed from the side or the front. When an architect designs a structure, he or she will create the project's plans and elevations. The elevations show what level the walls, floors, and other features of the building are placed on compared to the ground. They also indicate where doors and windows are located. The basic forms used to draw the elevations are called "shapes". There are four main shapes used in architectural drawings: rectangles, parallelograms, ovals, and circles. A rectangle is the most common shape for elevations. It can be drawn to scale or proportioned. Proportionally drawn elevations use dimensions such as height to width or length to depth to express the size of the room compared to its distance from a wall. Dimensions can also be expressed using fractional values (e.g., 1/2). Scaled elevations are usually not proportional because they show exactly how much space a particular room takes up rather than expressing its size relative to another object. Parallelograms are used to describe rooms with diagonal walls. An example would be a room with some floor-to-ceiling walls and some ceiling-to-floor walls.