Alatri is an Italian town and comune of the province of Frosinone in the region of Lazio, with c. 30,000 inhabitants. An ancient city of the Hern…Alatri is an Italian town and comune of the province of Frosinone in the region of Lazio, with c. 30,000 inhabitants. An ancient city of the Hernici, it is known for its megalithic acropolis. The area of the modern city was settled as early as the 2nd millennium BC.