A storefront or shopfront is the facade or entryway of a retail store located on the ground floor or street level of a commercial building, typically including one or more display windows. A storefront functions to attract visual attention to a business and its merchandise. Before the middle of 19th century, shop fronts did not have large display windows, but often included features such as awnings and bay windows to attract the attention of passersby. Modern storefronts with display windows developed at mid-century after architectural cast iron became widely available and glass manufacturers began producing large panes of glass at relatively low cost. The storefronts of commercial buildings often are substantially altered even when other architectural elements remain intact. Such alterations can adversely affect a historic building’s architectural and historic character. E-commerce websites are sometimes called “online storefronts” or “virtual storefronts”.