The hamlet of Treia is resting on the crest of a long, narrow hill looking onto a vast territory below which extends eastwards through downward sloping hills towards the Adriatic, while to the west, to the Marchigian Apennines.
The name derives from “Trea-Jana”, goddess of Greek/Sicilian origin the cult of whom was widespread in these lands in the past.
Founded by the Sabines probably around 380 B.C., the township rose in a place two kilometres from its present location, in the place now called Ss. Crocifisso.
Becoming first a Roman colony, around 109 B.C., the settlement was raised to the rank of municipality, quickly achieving remarkable military importance, as witnessed by the archaeological excavations and historic records of the past. Located on a byway of the Flaminia, the settlement enjoyed enormous economic and social benefit during the flourishing Roman Empire. However the well being reached was soon turned into sacking and destruction during the Barbaric conquests on their march towards Rome. The situation compelled the surviving populace to move to a safer position, taking refuge in three low hills not far from the Roman city, founding the present city which was named Montecchio from Monticulum or Monteclum, otherwise “Little mountain”, the name was kept until 1790 when Pius VI restored the ancient Roman name of Treia, conferring on it the title of “city”.
The township of Montecchio while always faithful to the Pontifical government, soon gave itself a typical commune system and extended its territory to include the three castles initially erected on the three hills; the castles of Onglavina, Elce and Cassero.
During this time, the city underwent mighty works of fortification thanks to the building of its still intact walls and fortress.
During the struggles between Papacy and Empire, the commune was often involved in sieges by the Ghibelline troops, in particular in 1239 by Enzo, illegitimate son of Federico II, which it bravely resisted. Again in 1263 by Corrado d'Antiochia who was actually taken prisoner by the city defenders in the battle of Vallesacco.
In the XIV century the town was placed under the Varano nobles, then under Francesco Sforza. In 1447, the Pope put it under Alfonso d'Arcona's authority, but quickly returned to be directly controlled by the Pontifical State until in 1550, Pope Giglio II ceded it to the Cardinal Cesi.
In 1778 some luminaries worked in he reconstitution of Sollevati Academy, started in 1430 with a poetic-literary purpose, changing the name to Georgica Academy. This was born with the aim “to give opera and encouragement to rational and practical study” which served to “improve agriculture and industry and to hold science, letters and art in honour”.
Thanks to the good work of these luminaries, the academy achieved important results in research and agricultural experimentation to make it famous throughout Europe. Due to the high level reached, the agricultural ministries of both France and Belgium contributed to the running costs and even Bonaparte was keenly interested in the Georgica.
Illustrious men of the calibre of Volta, Tiraboschi, Spallanzani, d'Alembert, Mommsen played a role in the academy.
In 1790, Pius VI conferred on Montecchio the title of city, restoring the ancient name of Treia. In 1798, together with other cities of the Pontifical State, Treia took part in the brief experience of the Roman Republic on the wishes of Napoleon, and, in 1860, after the battle of Castelfidardo, it became annexed to the Reign of Italy. 

Monuments