Palm Sunday morning, I had my Syrian Orthodox here; during their Liturgy they made several processions round the outside of the church, throwing flowers and singinging Hosanna. It set me thinking.
In our austere Roman tradition, the essential purpose of processing is usually to get from a point A to a point B. There can be other reasons - praying for the crops at the Rogations; processing the Sacrament for adoration, or Relics, Statues and Ikons to articulate the mutual relationship between heavenly patrons and their earthly fellow-citizens. Still, my instinct is that these things are historically secondary, and not so much core 'Roman' as the utilitarian need to get from one spot to another.
But I suspect that other traditions see a naturalness in walking round and round a holy site simply for the sake of its holiness. They did it in pre-Tiger Ireland; round and round a spot made sacred by saintly presence, saying the while the prescribed exercises. I remember doing this year by year as we stopped at the shrine of St Gobnait near Ballyvourney in West Cork, on our way to the blest Kingdom of the West, Co Kerry.
I suspect analogues could be found in Oriental Christianity, in Islam, in other non-Christian religions. Probably somebody somewhere has thought a great deal more about this than I have, because it's only just occurred to me. But I don't feel like perusing that old heathen Fraser ... he'd probably say it was Sun-worship, or something daft like that.
I welcome enlightenment.
[Anticlockwise, if you're wondering].