There is a wine for the first genuinely cold night of the year, the one where you give in and light the fire. It is red, it is Tuscan, and it comes from a single hilltop town south of Siena. The locals will tell you it is the greatest thing they make, and for once the local pride is hard to argue with. This is Brunello di Montalcino, and it is built for exactly this time of year.

Brunello has a reputation that arrives before the bottle does: serious, expensive, a wine for people who know. Some of that is fair and some of it is theatre. What most people actually want to know is simpler. What is it, why does it cost what it costs, and where on earth do you start. Here is the honest version, with a few bottles worth opening as the nights draw in.

One grape, one hill

Brunello di Montalcino is made from a single grape, Sangiovese, grown around the medieval town of Montalcino in southern Tuscany. Brunello is simply the local name for a particular strain of Sangiovese, and the rules of the appellation allow nothing else in the blend. No Cabernet, no Merlot, no softening international grapes. Just Sangiovese, and the place it is grown.

That place matters more than almost anything. Montalcino sits higher, warmer and drier than the Chianti hills to the north, close enough to the Tyrrhenian coast to catch a breeze and far enough south to ripen Sangiovese fully and reliably. In a grape that can turn thin and mean when it struggles, that dependable ripeness is everything. It is why a hill most people could not find on a map became one of the most famous addresses in Italian wine.

The story usually starts with one family. In the late nineteenth century the Biondi-Santi estate began bottling Sangiovese on its own, aged long and built to last, at a time when most Tuscan red was drunk young and cheerful. The idea was radical then: a Tuscan wine made not for the week but for the decade. It worked. More than a century later the template is unchanged, and Montalcino is lined with growers chasing the same patient ideal.

Why it costs what it costs

The price is the first thing people flinch at, so let us deal with it plainly. Brunello is expensive partly because the law insists on it. A Brunello cannot legally be sold until the fifth year after the harvest, with at least two of those years spent in oak, and a Riserva waits a year longer still. That is half a decade of a winemaker's money sitting in a cellar before a single bottle is sold, and the cost of that patience ends up in the price.

The rest is arithmetic of a familiar kind. The best sites are small and in demand, yields are kept low to concentrate the fruit, and the top single-vineyard bottlings are made in tiny quantities that collectors fall over themselves to buy. None of that makes Brunello a bargain, but nor does it make it a con. It is a wine where you tend to get what you pay for, which in a crowded market is no small thing.

Rosso, Brunello, Riserva: the ladder

Montalcino is unusually generous to the curious, because it offers the same wine at three heights. At the bottom of the ladder is Rosso di Montalcino, released young and priced well below its big brother: the same grape, the same hill, but softer, fruitier and ready to drink now. It is the single best way to meet the style without committing to a cellar or a splurge, and a good one is a far smarter midweek buy than a mediocre Chianti.

Above it sits Brunello proper, the main event, and this is where most people should spend their money. You do not have to climb to the very top to drink beautifully. A bottle like CastelGiocondo, from the Frescobaldi family's historic estate, one of the founding names of the appellation, gives you genuine Brunello from a famous address for a little over fifty pounds. At the summit are the Riservas and the single-vineyard crus, the wines that justify the reputation and the auction prices. Start low, climb when the occasion earns it.

Two schools, one hill

Spend any time in Montalcino and you will notice an old argument running through it, between the traditional and the modern. The traditionalists age their wine for a long time in large old oak casks called botti, which add little flavour of their own and let the Sangiovese speak: wines of perfume and transparency, all red cherry, dried rose, tobacco and a fine, savoury grip. Il Marroneto, made by Alessandro Mori on the cool northern edge of the town, is a benchmark of this style, a wine that wears its considerable power like a whisper.

The modernists lean into riper fruit and a more polished, velvety texture, sometimes with a touch of smaller French oak. Done well, as at Casanova di Neri, whose classic White Label has been made since 1978, the result is Brunello with the lights turned up: deeper, rounder, more immediately seductive, while keeping the acidity and grip that make the grape worth ageing. Neither camp is right. They are two accents of the same language, and the only way to find your dialect is to drink both.

When an evening genuinely deserves it, Montalcino has a top floor. A single-vineyard wine like Casanova di Neri's Cerretalto is the kind of bottle you open once a year, for the people who will notice. It is not an everyday purchase and it is not meant to be. But it is worth knowing it exists, if only so you have somewhere to aspire to when the Christmas lunch warrants something extraordinary.

How to drink it

Brunello rewards a little ceremony and punishes impatience. Young bottles are tightly wound, so give them air: an hour or two in a decanter, or a very large glass, lets the perfume unfurl and the tannins soften. Serve it cooler than a centrally heated room, somewhere around sixteen to eighteen degrees, which in practice means cooler than you think. And give it proper food. This is a wine that comes alive with roast meat, braised beef, wild boar ragù over pappardelle, or the Tuscan textbook answer: a thick, rare bistecca alla Fiorentina and a board of hard aged cheese.

If you want to place Brunello in the wider map of the grape, our guide to Sangiovese is the natural next step, and if you are drawn to Tuscany's rule-breakers there is always the story of the Super Tuscan. For the full sweep of the country, from Piedmont to Etna, start with our best Italian red wine guide.

Brunello is not complicated once you strip away the mystique. It is one grape, grown on one lucky hill, made with enough patience to be worth the wait. Pour a glass on the first cold night of the year, give it a decanter and a good dinner, and the reputation explains itself. You will understand, very quickly, why the people of Montalcino are so quietly, insufferably proud of it.