The rapid growth and accompanying pollution in Victorian cities caused great problems for architects including denial of light, overcrowding, awkward sites, noise, accessibility and visibility of buildings, and air pollution. Provision for "the sufficiency of window light supplied throughout the building" was addressed by the use of architectural devices: suspended first floor rooms, made possible by the use of iron-framed construction, skylights, extra windows and dormers, "borrowed lights" for interior spaces and glazed white bricks in conjunction with mosaic marble paving in areas where the light was "less strong". Clear glass was used in important rooms, with light-coloured tints for coloured glazing, as "the sky of Manchester does not favour the employment of deeply stained glass."