I've visited two 'kilometre zero' sites this year, in Paris and in Madrid. The one in Paris is just in front of Notre Dame cathedral; the one in Madrid is in the Puerta del Sol.
They're not impressive sites; in Paris there's just a little circular motif in the pavement. If you didn't know what it is, you'd think it's a small manhole cover.
But there's something immensely poetic in the idea of a kilometre zero - the point from which all road distances are measured. It's like the omphalos, or navel of the world, at Delphi, or the medieval Christian idea of Jerusalem as the centre of the world. It seems, in a way, to focus the entire energies of a country in a single point.
And then, in a rather post-modern way, there's the irony that with all this going on, the kilometre zero itself is such a banal object.
The 'kilometre zero' that really brings together the mapping and administration dimension with that sacred, shamanic dimension, though, is one I haven't visited; Delhi. Here, India's kilometre zero is built on the site of the cremation of Mahatma Gandhi - the father of the nation. It's as sacred in its way as the Lapis Niger in Rome, the original sacred centre of the city in the Forum (the 'new' kilometre zero is on top of the Capitoline Hill).