The last Wednesday in August marks Spain’s messiest festival. Held in Buñol, an otherwise drab industrial town 40km west of Valencia. La Tomatina is a tomato-throwing orgy that causes the population to swell to more than 40,000 visitors in a town of just 9,000 inhabitants.

The mayhem takes place on the town's main square and Calle del Cid. At precisely 1100 local time a large greased pole with a ham attached to the end of it is hoisted into the air, and there is a mad scramble as people struggle against each other to pull it down. Once this is achieved, a rocket swooshes skywards and more than 100 tonnes of ripe, squishy tomatoes are tipped from trucks to the waiting crowd. For precisely one hour, until a second rocket is fired, everyone joins in a frenzied, cheerful, anarchic tomato battle. After being pounded with pulp, expect to be sluiced down with hoses by the local fire brigade.

The crazy food-fighting festival of La Tomatina began in 1945, but it is not known why. Locals have numerous theories, including the popular tale of disgruntled townsfolk attacking city councilmen during a town celebration. However, it could also be attributed to anything from an anti-Franco protest or simply a fun food fight between friends. Whichever way it started, the townsfolk of Buñol enjoyed it so much that it was repeated year after year, finally becoming an officially recognised celebration in 1952. Despite being canned briefly during the 1970s for having no religious significance, it has returned full-throttle every year.

The festival is now held in honour of the town's patron saint, St Louis Bertrand, and the Mare de Deu dels Desemparats (Mother of God of the Defenceless).

Most people come for the day, arriving on the morning train from Valencia and heading back in the afternoon. But if you want the full La Tomatina experience, stay for the week-long celebration, which involve music, dancing, parades and fireworks. The night before the fight, a paella cooking competition is held where women traditionally dress in white, and men forego shirts altogether.

Protection for the fight is recommended wear old clothes and shoes and a pair of goggles to protect your eyes. As you are hosed down with water after, a change of clothes is a good idea, although warm Valencia temperatures will have you dry in no time.

What you don't bring to La Tomatina is also important. The crazed tomato-throwers take no prisoners; cameras are seen as positive invitations to pelt the owner. Women should be aware that a wet T-shirt competition is an unofficial part of the day. Tomatoes are supplied, but ensure they are squashed or fruit might not be the only bruised bodies in town.

If you do not fancy being showered with soggy tomatoes, you can watch the spectacle in dry comfort on Canal 9, Valencia's local TV channel. Or, you could avail yourself for the more painful orange-throwing festival, the Battle of the Oranges, held in the northern Italian town of Ivrea every February.

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