Cittaducale has 6,900 inhabitants in the plain of San Vittorino, on the via Salaria, with Monte Terminillo behind it. It is a town founded on the drawing board: Charles II of Anjou willed it in 1308, and called it Città Ducale in honour of his son Robert, duke of Calabria. He is still on the coat of arms, on horseback, tracing the outline of the town with the tip of his sceptre. The plan is that of a Roman castrum — elliptical, with two streets crossing in the square — because it had to be a fortress: it was the northernmost point of the Kingdom of Naples, guarding the border with the Papal State.
That border lasted almost into living memory. Cittaducale was Abruzzese, and in the province of L'Aquila, for more than six centuries; only in 1927, with the reorganisation of the provinces, did it pass to Lazio and to the new province of Rieti. At the hamlet of Santa Rufina stood the customs house. Today the town is known above all for water: the Peschiera springs rise here, second in Italy by volume, and from here starts the aqueduct that carries them ninety kilometres to Rome, where they provide almost all the water the capital drinks.