 The central court could form a simple courtyard, but many companies preferred to roof over the courtyard with glass to produce an atrium for shops and restaurants.Rents for these shops were up to five or six times that for office space, and made an important difference to the income from a property.Chicago skyscraper windows were also a feature of the style; these were large, fixed windows flanked by smaller sash windows on either side, which provided access to sunlight and adequate ventilation.