More people across the world are living in cities than ever before. Cities are both places of historical significance and the engines of the world’s economy. They’re also home to some of the greatest treasures and buildings that mankind has created. Cities are wonderful subjects for photography. They offer a variety of subjects suitable for both straight and HDR photography, including architectural, street and night photography. The structure, angles and texture you get with architectural photography make it unique and very engaging.
source: http://www.smashingmagazine.com/2009/02/01/35-examples-of-beautiful-city-photography/