The Roman Period Collection encompasses material evidence of the culture from the period of Roman rule, collected from all over Istria. Although Roman campaigns against the Histri, the indigenous population of the peninsula, began as early as the late 3rd century BCE, it was the fall of Nesactium, the primary Histrian settlement and the seat of their king Epulon, in 177 BCE that marked the turning point in the Romanisation of Istria. The process of Romanisation intensified significantly under Caesar, in the mid-1st century BCE, when the cadastral division of land was established, and the old Histrian settlements of Pola and Parentium were made colonies of Roman citizens. These cities became hubs of social, administrative, religious, and commercial life, designed according to developed Roman urban standards. In the Roman colonies, as centres of Romanisation, the Latin language and script, Roman currency, measurement system, religious and other customs were soon adopted. Pula became the most important city in Istria, and its exceptional wealth was manifested by the erection of a lavishly decorated forum with temples, the Arch of the Sergii, the city walls, two theatres, and a magnificent amphitheatre.
Few Roman monuments have survived to this day; most have been destroyed, demolished, or secondarily used for other purposes. The effort invested in collecting, investigating, and preserving the material remains of antiquity in Istria, from the first half of the 19th century to this day, has produced a rich collection of ancient artefacts made of various materials. Standing out among the small utilitarian objects made of ceramics, stone, metal, bone, and glass, are the stone monuments (funerary, votive, honorary, architectural)—an inexhaustible source of information about the life and the social and ethnic structure of the Istrian population of that time.
The collection also includes many amphorae, both of local production (Fažana, Loron) and those imported from various parts of the Roman Empire. Among them are more than 2,000 mostly intact amphorae found in Pula's St Theodore quarter, the largest terrestrial amphora site in the world. The amphorae were installed for drainage purposes in a Roman era quarter that included a luxurious domus, public thermae, and a sanctuary of Hercules.