Roger Mills ran the Paris marathon last week. How does it compare with London's?
About eight kilometres into last Saturday's Paris marathon I saw an elegant, fiftysomething woman trying to cross the road. She knew she faced a major wait: 22,000 closely packed runners make a formidable obstacle. "C'est pas possible," I heard her muttering bitterly as I went past.

Parisians aren't terribly interested in their marathon. Most of them don't even know it is happening, and the few hundreds who turn out to watch mostly look on in bemused silence. You get the odd pocket of support - the French fire service, who man a series of water points along the way, cheer you along energetically. But po-facedness is the norm.

In Paris there aren't any "fun" runners as there are in London - the bizarre collection of wannabe eccentrics that makes the run look like 20 circuses suffering a catastrophic scheduling coincidence. In the first mile of the London race last year I saw a mummy, a Roman centurion, three rhinos and a man dressed as a carrot. The carrot, annoyingly, overtook me later. All I saw by way of comparison in Paris were a husband and wife team self-consciously sporting Mickey Mouse ears, and a man in a jester's cap.

The London marathon is a 26-mile carnival. Every pub has a band or a sound system pumping out morale-inflating music. Big crowds flank many parts of the route, generating what feels like stadium decibel levels. Lines of children hold out their hands wanting you to touch them as you run by. Again and again you come across spectators who, although they have no official connection with the race, have set up tables of food and drinks for any runner who wants them. If the election campaign leaves you feeling that human nature is in a state of irreparable decay, a visit to tomorrow's London marathon will be a powerful antidote.

The Paris run may lack this spirit. But there are compensations. The marathon route is stunning. You start at the top of the Champs Elysees and then progress through the heart of the city past the Tuileries, the Louvre and down to the river for a mile or so before wheeling left to the Place de la Bastille. Where you are running is normally a gridlocked nightmare, and that, plus the fact that this is the sort of route taken by presidential cavalcades, gives you a delicious sense of trespassing.

The Paris route is good for discoveries, too - how many visitors ever visit the eastern Bois de Vincennes (miles of woodland, a zoo and an imposing chateau), or spend much time in the Bois de Boulogne? - though tourism doesn't have to be this painful.

Would I do the Paris run again? I don't think so. Marathon running is hard work and the atmosphere you run in makes all the difference. I'd go for the carnival every time.