Its motto is: Est mihi libertas papalis et imperialis.
Velletri is renowned as one of the main centres for wine production in the Latium.
The origins of Velletri (ancient Velitrae) are uncertain. A settlement existed on the site from pre-historic times, though scholars debate if its inhabitants were Etruscan or Latin. In the year 494 BC, while in danger due to Volscian pressure, the city was garrisoned with colonist soldiers by the Romans; Rome was mainly interested in stopping Volscian expansion in Latium. Subsequently, after the First Latin War in the 338 BC, Velitrae was deprived of city walls as Rome achieved sovereignty over its territory.
During the Roman period, patricians built several villas in it. The city had also several temples and an amphitheatre. The family (gens) Octavia, to which the first Roman Emperor Augustus belonged, came from Velitrae, and the future emperor spent his youth there.
Velletri began to decay after its sack by Alaric the Goth in 410 CE. In the 5th century it was the seat of a bishopric and in the following one it became an imperial city after the Byzantine reconquest of Italy. In the Middle Ages it started a difficult recover, culminating in the 12th century with its declaration as a free commune. In the 14th and in the first half of the 15th centuries Velletri fought against the commune of Rome and the barons of Lazio, and later became part of the Papal States.
The first pawnshop of the world was opened in Velletri in the 15th century.
In 1744 Velletri and its surroundings were the theatre of a battle between the Spanish and the Austrian Army, during the war between the Habsburg and the Bourbon. After the French Revolution, Velletri rebelled and it was proclaimed a Republic. Later changed side and 900 of its citizens resisted in Castelgandolfo the siege by Joachim Murat. The Republic lasted till 1814, and was briefly revamped in 1849.
In 1862, the Roma and Velletri railroad was opened for service.