The city of Alatri stands on a hill in the heart of Ciociaria, at the foot of the mountains Ernici constituting the natural border between Lazio and Abruzzo. The vast territory alatrense, flat or hilly and mountainous south for the remainder, also includes the administrative area of ​​”Pratelle”, between the town of Collepardo and that of Morino, where there is the highest altitude of 2,064 ms. lm (upstream “Passeggio”); from here slopes down to a minimum of 175 m of the plain of “Tecchiena”, including its extension much of the basin of the river What a tributary of the bag which flows east of the city center in north-south direction. According to the Geological Map of Italy prepared by the Geological Survey of Italy, the territory alatrense is composed largely of soils “yellowish-white granular limestone with big features of the Senonian rudist” In addition, some areas are formed by limestone yellowish perhaps belonging to the lower Miocene sandstones and clayey or calcareous and sometimes gessifere. The lower areas of the territory, as the valley of the river “Cavariccio”, are formed from volcanic tuffs (pozzolana and tuff). The human presence in the territory of Alatri is ascertained by calcolito period. The French archaeologist Louis-Charles-François Petit-Radel (1756_1836) placed the date of the founding of Alatri before the Second Cologne Pelasgian, dating back to 1539 BC.