Dom Joly: The National? Pfff. Try this Siena thriller

I was wandering around the Piazza Del Campo in Siena this week marvelling at how they could possibly allow a horse race to take place there.

The Campo is the central square, a gently sloping space in the shape of a shell and entirely surrounded by medieval buildings and towers. A more stunning setting would be difficult to find and yet twice very year (2 July and 16 August) the square is the unlikely location for the Palio, where ten bareback riders and their mounts race round it for the honour of their contrada.

The city is divided into seventeen of these neighbourhoods, originally set up to help with local defence. If you are born in Siena you have two baptisms, one in church and one in your contrada's fountain – they take it very seriously. The rivalry is fierce and passions run high, even for Italians. Jockeys are usually chosen from Sicily as they have a reputation for being fine horsemen and it is believed they will be less likely to bribed by a rival contrada.

Quite why Sicilians are so trusted nobody here will explain to me. I guess that my mental image of an island rife with homicidal mafiosi must be false. These tiny jockeys are paid huge sums and often encouraged to noble riders from opposing contrada – maybe this is where their Sicilian skills come in. The night before the race horses are lead around their respective Contrada, taken to church to be blessed and are the guests of honour at banquets.

This is probably the only race in the world where a riderless horse can win. Even if the Sicilian is thrown off, should his horse romp in first, then it is known as a "scosso" – that means "shaken" or "upset". I'd have thought this would be a more appropriate name for the fallen jockey. The horse still gets another banquet, I couldn't find out what happens to the unseated Sicilian, but if you'd paid a vast amount of money for the little guy only for him to fall off and the horse demonstrate that he could do it on his own some sort of refund might be in order.

Maybe the excitement of winning blinds the contrade to this particular problem. The prize is the palio itself – a painted banner of the Virgin Mary. A celebrated artist is chosen to make a different one each year. It is rumoured that Damien Hirst was approached but his contribution of a Virgin Mary made from horse guts and eyeballs was not appreciated.

There have been efforts recently to make the race a little safer for both rider and horse with cushions being placed on some of the tighter corners but this is thought by many Italians to be ludicrous. On the day of the race itself, the square is rammed with spectators from around the world – every available inch of space is taken and the whole scene turns into what British authorities would consider to be the biggest health and safety headache imaginable. For Italians however, such concerns are for feeble bureaucrats. I think it's wonderful that such an event still takes place.

Imagine Golden Square in Soho (not really as architecturally impressive) being taken over twice a year for a horse race. Jockeys would be brought in especially from the Isle Of Man and different media sections of Soho would square up to each other. The great Avid Editors of Wardour Street would race the Runners of Dean Street and the Gay Baristas of Frith.

The night before all the horses and jockeys would have a banquet in Soho House where one of them (maybe representing the TV producers of Charing Cross Road) would suffer cocaine psychosis and be withdrawn.

It would never happen. Traffic wardens would slap tickets on horses, council officials would ban people from leaning out of windows, police would swoop on gamblers and it would rain solidly throughout the whole event.

Bad luck would also follow Tim Henman, who had spent two years on the Isle of Man training for the event. The headlines in the next day's tabloids would proclaim: "Henman's hideous accident – star jockey trampled by horses after falling at Starbucks Corner."

Meanwhile, back in Siena, two months before the first Palio, I sit at a cafe in the Campo and revel in the very existence of such an event.

I'm a scooter star

Why isn't there an international federation for urban Vespa racing? The Italians would be fabulous at the sport but I for one would be nipping at their heels ... beep beep.