The town of Segni is located on a hilltop in the Monti Lepini mountain range, overlooking the Sacco River valley to the east of Rome. It should come as no surprise that the town is twinned with the village of Mykines, in Greece near the famous site of Mycenae.

Like its Grecian counterpart, Segni is surrounded by huge polygonal walls, also known as cyclopean walls for their sheer size and extent. They are believed to date back to the 6th century B.C. During this period, the town was a stronghold of the Volscian people.

According to Livy in 513 B.C., Roman King, Lucius Tarquinius Superbus, established a colony and garrison in Segni then known as Signia to protect eastern access to Rome. It became a fully recognized Roman municipium in 89 B.C. The original city walls might have been strengthened using the archaic technique during the Punic Wars.

The most important gate is the so-called Saracen Gate, crowned by a huge limestone monolith which is nine feet (three meters) long, Segni's own version of the Lion Gate in Mycenae. The entrance is more than six feet (two meters high). The gate appears quite frequently in sketches and illustrations from the Grand Tour that took place during the 17th and 18th centuries.

Several other gates, including the refurbished Porta Maggiore (the main access to the old town), are located along the perimeter of the city walls. The megalithic blocks were also used as foundation stones for the church of Saint Peter, which was constructed atop an ancient acropolis. 

Polygonal walls can also be found in the regional towns of Anagni, Alatri, Artena, and Ferentino but Segni's are probably the most spectacular.