The great cities of the Islamic world form a chain reaching from northern India to the Andalusian region in modern Spain, encompassing Marrakech, Cairo, Damascus and Baghdad along the way. These places were constructed along trade routes, some pre-dating the coming of Islam, others built as a result of its conquest of new areas. Mainly inland, their initial purpose was to provide a space for exchange and respite for merchants moving across the great trading routes of North Africa and the Middle East. As these cities developed they grew to be leading centres of learning both for scholars and artisans.
As merchants and students moved between cities they spread with them not only their knowledge of science and religion but also an understanding of architecture. From this a certain language of design developed, unifying and identifying Muslim places across the chain. These Islamic architectural elements are most noticeable in the shape of mosques, with their distinctive forms of courtyards, minarets and domes, but are also reflected at a wider scale across towns and cities. Alongside this architectural language closer inspection reveals individual touches, where each region and city developed its own style, using different building materials and decoration to express its identity and culture. Some of the most striking examples of this are the Djenne Mosque in Mali and the palace of Al-Hambra in Granada, Spain.
The elements of the buildings and cities were not only designed for their great beauty but also held within them a physical expression of Islamic life and spiritualism. The cities were not simply a collection of buildings, peppered throughout a public area, but were a collective of buildings and gardens. The person moving through them would experience a flow between large open spaces, built to accommodate collective gatherings, and smaller more intimate areas in the market or in courtyards.  The mosque itself would be flanked by minarets, great tall towers marking both the territory of the building and reaching up, connecting the horizontal flat earth with the heavens. The final culmination of this flow of space would be the prayer hall of the mosque, a place where the earth, with its four walls, and four seasons, meets heaven, a universal circle reaching up into the sky.
One of the most remarkable Islamic cities is Isfahan (also called Esfahan or Hispahan), today the third largest city in Iran. Set against a backdrop of snow-capped mountains, the city is populated by both Islamic and pre-Islamic buildings. Although it has existed in some form since pre-historic times, it was not until the era of Shah Abbas I, in the late sixteenth century that much of what still stands in the city was built. It was Shah Abbas who decided to make Isfahan the capital of his Safavid dynasty and to build a breath-taking city of parks, libraries and mosques remarkable in their scale and the beauty of their decoration. At this time Isfahan had a population of around 600,000 people with an astonishing number of buildings: 160 mosques, 48 religious schools, 1,800 shops and over 270 public baths. It had become such a melting pot of travellers and cultures that it was also referred to as 'Nesf-e-Jahan' meaning 'half the world' in Persian.
The buildings of Isfahan demonstrate some of the particular artistic characteristics that developed in the Persian region. The gates of the mosques, or 'eivans' are massive in scale and decorated in vibrant coloured tile work. On a practical level these mosaics protected the bricks beneath but also lifted the buildings with bright colour and intricate geometric designs. The artisans' level of skill reached such a height that they were able to overlay all the small niches, concave arches and domes of the buildings with minutely detailed and complex patterns. Some of these also depicted calligraphy, translated from the page to the wall in tile work. This calligraphy elevated the beauty of the buildings yet further by emblazoning them with the word of God. Many of the artisans who created these buildings and their decoration were thought to have been influenced by Sufism, a spiritual exploration of Islam. This architecture was not simply an exercise in building cities but also an attempt to open souls to the wonder of the divine through the most extraordinary scale and beauty of the spaces they created.
Isfahan was awarded UNESCO world heritage status in 1979 both because of its architectural significance and as a reflection of the tangible link between its design and Islamic belief and customs.
 A. Hourani A History of the Arab Peoples. London: Faber and Faber 1991
 D.B. Carruthers 'Architecture Is Space: The Space-Positive Tradition,' Journal of Architectural Education. 1986, 39 (3):17-23
 'The Alchemy of the Mosque', Isfahan
 'Isfahan Is Half The World,' Saudi Aramco World. 1962, 13(1)
 'The Alchemy of the Mosque', Isfahan
 UNESCO World Heritage, Meidan Emam, Esfahan
Picture 1: "dome, lotfollah mosque, isfahan oct 2007" by seier+seier+seier, Flickr
Picture 2: Isfahan/ Jame Mosque/ Tile works, by Horizon, Flickr
Picture 3: Pòrtic, Mesquita del Xa, Isfahan, by Sebastia Girlat, Flickr