The cemetery of the Great Mosque in Kairouan, south of Tunis. This is a beautiful city, but no photograph I have seen (I haven’t waded through Flickr) does justice to its pastel delicacy. It is easy to understand why Klee loved it. It is the fourth holiest city in the Sunni Muslim world, after Mecca, Medina and Jerusalem.
Every city – or, it might be more accurate to say, every city before the present age of mechanization – has been, among other things, a holy city in some degree. Religion is an intrinsic and distinctive element in human nature as I see it, and it is unquestionable that, until not more than about two hundred years ago, every city has had a religious aspect among others. No city at any time or place before the outbreak and spread of the Industrial Revolution has ever been either a commercial, an industrial, a political, a military, or a religious city exclusively. [...] The mechanized city, which made its first appearance in eighteenth-century Britain, has been peculiar, so far, in either lacking the traditional religious facet of a city altogether or retaining it, if it has retained it, only in a vestigial form.
Abydos (Ancient Egyptian religion)
An-Najaf (Shia Islam)
Belfast, Northern Ireland, UK (Dispensational Christianity) [Is Belfast holy?]
Cusco (Ancient Incan religion)
Gaya (Buddhism, Hinduism)
Hebron (Judaism, Islam)
Jerusalem (Judaism, Christianity, Islam)
Karbala (Shia Islam)
Lhasa (Tibetan Buddhism)
Mashhad (Shia Islam)
Najaf (Shia Islam)
Nippur (Ancient Mesopotamian religions)
Poo Pathi (Hinduism)
Qom (Shia Islam)
Rajgir (Buddhism, Jainism)
Rome (Ancient Roman religion (polytheistic), Christianity)
Varanasi (Hinduism, as well as Buddhism, Jainism, and Sikhism in varying degrees)
: Wikipedia’s list.
Istanbul, I suppose, is an ex-holy city.
Cities on the Move, OUP, 1970