The hip hop guide to Tuscany's treasures

The half-term holidays are fast approaching. But how do you keep all the family entertained?

Can Duccio di Buoninsegna (b 1255) and Marshall Mathers III (b 1972) of 8 Mile, Detroit, ever occupy the same space? It is not a question that comes up often. But let's put it another way – can a couple of wannabe street-smart teenagers from south London share a holiday with their art-worshipping septuagenarian granny in Tuscany?

It reads like the bare-bones premise of a wacky new reality TV show, and like all good reality formats it offers the likelihood of an explosion. The dramatis personae are my mother (aka granny) and my sons Tom (16) and Niko (12). The stage is set in central Tuscany, near San Gimignano, and though I am the de facto director I have no idea if this show will end as a comedy or tragedy.

We are staying at a converted farmhouse, the Borgo di Mariano, just outside Castel San Gimignano. It is a one-grocery, two-bar kind of sleepy hilltop village, which is more or less equidistant from San Gimignano and Volterra. Siena is about 25 miles away – but I decide we should not attempt an immediate assault on the cultural peak without first taking a foothill or two.

Seen from a distance, the bristling towers of San Gimignano give it the appearance of an architectural hedgehog. These days there are a mere 14 towers, but once there were 72 – a testament to the phallus obsession of the town's medieval clan chiefs who sought prestige on the simple basis that size matters.

The towers literally raised the profile of San Gimignano and, given its location between Florence and Siena, it would be unrealistic to expect it to escape the attention of the summer hordes. Returning to San Gimignano after a good few years, I am struck by the changes. The citadel is now ringed by car parks and getting to them can involve sitting in rush-hour style traffic.

The town's basilica is still a showcase of medieval art – or, as Niko puts it, is "boring". I persuade Tom to compare the 14th-century fresco cycles on the south and north walls. They were painted 30 years apart and in my reckoning the earlier paintings by the school of Simone Martini are more accomplished. Tom seems prepared to consider this proposition for the flicker of a moment. Then granny wades in, unleashing a superheated blast of art history on the poor boy. He wilts under the onslaught.

Back at the Borgo, the boys rediscover the will to live by splashing noisily in the pool. The sunset is magnificent, throwing lurid pink and violet feathers across the sky. In the fading light, the gently undulating hills recede, ridge after ridge to a smoky vanishing point. It is the backdrop of countless renaissance paintings.

In the apartment later the boys are picking out an Eminem tune on the iPod. Wily old granny senses an opportunity. "Who is this singer?" she asks. Soon they are in deep conversation. "I have an idea," she says brightly, "we can play a game. You teach me about Eminem, and I will tell you all about art and churches – then you can test me, and I will test you. Whoever has the highest score wins." Neither of the boys can resist the bait.

Over breakfast in the morning, Niko is quizzing granny.

"What is Eminem's real name?" he asks.

"Michael?" she ventures. "Or is it Martin? Martin Matthews?"

"Wrong!" says Niko delightedly.

"Your turn," says granny quickly. "What is a blind arch?"

Volterra is the next citadel in our campaign. Most of the day is spent playing tennis and goofing around the pool; we set off only after the heat of the afternoon has peaked. The town has a commanding position on a ridge; its massive walls are a reminder of Volterra's resistance to the hegemony of Florence. As its name suggests this is a town of earth and wind, and the squat 13th-century Palazzo dei Priori

(town hall) has an austere elemental look about it.

It is less overrun by tourists than San Gimignano; local families trail around the piazza during the passeggiata; old men swap news in the last beams of the evening sun, while a row of blue-rinsed grannies perches on a stone bench built into the façade of the town hall.

Tom and Niko sit on the pavement outside the slightly ragged duomo and seem content to spend minutes simply absorbing the atmosphere. From a piazzetta next to the city walls we look out on the jumble of warm terracotta rooftops and a commanding view over the surrounding countryside. Granny and I sip Campari and soda sundowners in the eccentric little Caffè dei Fornelli. Tom is in reflective mood. "I like this place much better than San Gimignano," he says. Granny turns to Niko, "What is the name of the central aisle in a church?" "Nave," he shoots back.

We are ready for the Big One – Siena. The sheer spectacle of Il Campo, the central piazza where the annual Palio horse races are held, draws appreciative noises from the boys. It is laid out like a huge shell in front of the implacable gothic presence of the Palazzo Comunale, which is topped by the 335ft Torre del Mangia – designed with the intention of making rival Florence feel inadequate. Competitive erections seem to have been a popular pastime in these parts.

We find it remarkably easy to dodge the crowds by nipping behind the tower into the Piazza del Mercato and on through the Porta Giustizia to the Orto de' Pecci, an extraordinary green space within the walls of Siena that seems to remain invisible to most tourists. The gardens are run by a co-operative called La Proposta which has the mission of rehabilitating people with "social" problems such as former addicts and ex-offenders. They manage organic allotments, a small farm, a falconry and a nursery. We have a very relaxed lunch in their patio restaurant, All'Orto de' Pecci, to the accompaniment of grunting pigs, goats and cockerels. We could be in the heart of the country, but are amazingly just minutes from the crush of the Piazza del Campo.

Fortified and braced, we take on Siena's magnificent duomo. From the moment you step in, it is almost overwhelming. Every inch of space is screaming for attention; the black-and-white striped stonework that hoops around the massive composite pillars, the deep-blue painted vaults with gold stars, the 56 inlaid stone panels of the floor. All before you register the frescoes and sculptures by the big hitters – Donatello's St John the Baptist, Pisano's pulpit and Pinturicchio's frescoes in the Piccolomini Library. Two hours spent in the cathedral draws complaints from the boys and we have yet to see Siena's greatest treasure.

Duccio's Maesta (Madonna and Child in Majesty) is displayed next door in a museum. The sheer size (7ft by 13ft) is impressive. A barrier requires us to maintain a respectful distance, but thankfully there is no protective glass screen and the richness of the rose and gold tones is dazzling. Unbelievably, there is no one else in the room; no doubt if Dan Brown was to weave the Maesta into another of his nonsensical bestsellers it would catch on. For the moment, though, we have Duccio to ourselves, which feels a huge privilege to granny and me, but I am conscious we are now on borrowed time with Tom and Niko.

They get their reward at Fattoria di Voltrona, an agriturismo near San Gimignano, where we have been invited to go riding. Horses are a thing of mystery to the boys and me – granny has wisely decided to sit this one out. We are assured that our mounts are super docile. They were imported from Iceland, and our charming riding instructor, Linda, has been imported from Sweden. The landscape, though, is quintessential Tuscany.

We set off in the creamy light of late afternoon and it is immediately clear that we are in one of the most beautiful places on earth. Linda shows patience above and beyond the call of duty – marshalling the city slickers – explaining how to brake and steer. But the horses know exactly what to do and what they do is ignore us. Linda also explains that Icelandic horses have five gaits, where others only have three. We can try one of the special gaits, she says, and before I have a chance to panic we are doing the tölt along the edge of a vineyard. We are cutting comical figures in a sublime setting. The plump little Thelwell horses swing their left and right set of legs alternately; it looks hilarious but the ride is surprisingly smooth. Nobody falls off, which is a bonus.

We are in a garden of earthly delight. The gently folding hills are dressed in oak forests, fields of sunflowers, grass meadows, vines and olive groves offering an infinite palette of greens, browns and gold. Cypress avenues follow ancient cart tracks up from the valleys to the ridges. On a distant hilltop, the evening-reddened towers of San Gimignano rise into a clear blue sky. On horseback you feel connected, a part of a landscape that seems unchanged in a thousand years.

It is dark when we join granny for dinner on the Fattoria's terrace. The cicadas have set up a standing wave of noise around the tables. Their metallic whistle and reply are quite hypnotic. Over pasta, Niko catches her with a question, "What is Eminem's real name?" "Marshall Mathers," she says without missing a beat. "Now Tom, can you tell me what an arcaded corbel table is?" To be continued.

Compact Facts

How to get there

Sankha Guha and family were guests of specialist rental agency Interhome (020-8780 6629; interhome.co.uk ). It offers a four-room apartment with shared swimming pool at the rustic Borgo di Mariano farm, near San Gimignano, with prices starting at £533 for seven nights, or from £207 for three nights, for up to six people sharing. Quote reference IT5257.250.10. Flights to Pisa can be arranged.

Avis (08445 818181; avis.co.uk ) offers a week's car rental from £153.

Further information

For horse riding, contact Fattoria di Voltrona ( voltrona.com).

Italian State Tourist Board (020-7408 1254; italiantourist board.co.uk ).