When part of the urban structure undergoes change it is a challenge to retain or to create a well proportioned visual harmony and maintain the coherent use of space.
Industrial and technical developments presented challenges that brought huge changes to 19th- and early 20th-century societies. This provided architects, as creators of structures in the built environment, with new tasks to create building types that would meet the needs of the modern age, greatly altering the urban web as well. The presence of European communities in the Arab and Ottoman world altered the languages of both urban and landscape architecture.
Traditional Islamic city-construction had focused on religious-pious buildings, such as mosques, mosque complexes and other devotional edifices, but in the 19th century new private and public buildings in the Western style marked the changing times. The railways that connected far-away lands were represented by magnificent railway stations, high-tech constructions that celebrated the materialism, technical innovations and achievements of the era: the Bourse signalled the new age of the money markets, harbours were built to accommodate trade and commerce; the post office pointed to modern communications; Western-type hotels were built for tourists and other buildings housed migrants who had settled in particular areas; council officials directed city life from municipal buildings; and museums, opera houses and theatres were constructed to serve a new institutionalised culture and to transmit the collective memory. New types of hospitals and military buildings emerged, as did public clocks and clock towers, which not only provided citizens with a reference to the time but helped to orientate them as well in the ever-growing city.