The term 'Narrow Shelf of a Building' can be summarized as a 'LEDGE'. A LEDGE is a narrow shelf or strip of land that projects from a wall or other structure. It is typically used to provide support for items such as books, pictures, ornaments, and other objects. LEDGE shelves are commonly found in buildings, both indoors and outdoors, and can be made from a variety of materials, including wood, metal, and stone.