The document discusses the physical components of open spaces, including walls, floors, roofs, and furniture. It describes walls as defining the shape and size of a space and directing movement. Floors can be flat, multi-level, or made of different materials depending on the space's use. Roofs are usually the sky but may be covered. Furniture includes hardscape elements like lighting, signs, sculptures, and fountains as well as softscape elements like trees and plants, which provide shade, act as landmarks, and direct movement and vision.