Two and a half kilometres in the centre of Turin cross two thousand years without ever leaving walking distance. The route starts at the Palazzo Reale, seat of the House of Savoy and briefly of the Kingdom of Italy, where the royal apartments sit beside Guarini’s daring dome for the Holy Shroud and a major armoury. It continues to the Museo Egizio, the world’s oldest museum devoted entirely to ancient Egypt and the second-largest Egyptological collection anywhere. Then two Baroque interiors: the Real Chiesa di San Lorenzo, one of the masterpieces of European Baroque, and the seventeenth-century Palazzo Falletti di Barolo. It ends at the Porta Palatina, the Roman gate of the first century BC and one of the best-preserved city gates in the world. Court, collection, church and gate: four ways the same city has kept hold of what it was.