That enthusiastic hill-walker Leonardo da Vinci marked the place in large letters on the map he drew of Tuscany, which is now in Windsor Castle library. Here is a perfect circle of walls with a steep drop to their base, a tight but roomy mass of churches, domestic towers, old four-storey tenements, flagged streets, deep-arched arcades – in other words, an intact Tuscan hill-town. With one difference: the population is indifferent to the occasional visitor.