Tyler Cowen skeptically quotes in Marginal Revolution from the new book by Chris Wickham – “The Inheritance of Rome: A History of Europe from 400 to 1000”:
“The other important feature of the Great Mosque was that, as a space, it was closed off to the outside. Roman cities were structured by wide streets leading to central forum areas, to which processions led and where public participation could be considerable, as continued to be the case in Constantinople for centuries. Amphitheatres (in the West), theatres and racetracks were other major venues for public activity, and the Hippodrome of Constantinople carried on this tradition for a long time. In the Islamic world, the mosque courtyard took over from all of these; major political events, like collective oaths of loyalty, took place there, not in any secular location. And the Arab states did not use processions as a major part of their political legitimization; the assembly in the mosque courtyard was sufficient for that. The need for wide boulevards ended; pre-Islamic Syrian and Palestinian colonnades were quite quickly filled in with shops in the eighth century, some of them commissioned as public amenities by caliphs. The narrow streets of Islamic cities resulted directly from this, for there was no public interest involved in keeping them clear from obstructions like vendors’ stalls, beyond a certain minimum (enough for two loaded pack animals to pass each other, later jurists said). Public display came to be focused on the mosque, and secondarily, rulers’ palaces and city gates, rather on the cityscape as a whole…The caliph and his advisers were nonetheless making a set of conscious symbolic and political points by organizing the Great Mosque as they did; and the way the public space in Islamic cities change, to focus so exclusively on mosques…would have seemed to them auspicious and fitting.”
I don’t know much about urban history of Rome or Greece. Someone in the comments there mentioned chariots, an interesting point worth looking into. But I can say with certainty that historic European capitals were as dense as the cities in the Middle East. Many European cities where build predominantly with wood and burned down. European cities were developed over the old dense grid. For example for military and aesthetic reasons Napoleon III commissioned Baron Haussmann to cut the famous boulevards through the historic maze of Paris. Many “modern” cities copied French boulevards rather literally. For example Commonwealth Ave. in Boston or Eastern Parkway in Brooklyn, the latter comes complete with an arch.
It might as well be true that the classical Roman parades where not part of the Arabic culture but it would hardly excuse or explain the density. More interesting question is if Islam’s Mosque plagiarized from Judaism were designed to mirror the traditional urban role of the Jerusalem Temple?
Further reading: