Oppidum is a Latin word meaning the main settlement in any
administrative area of ancient Rome, and applied more generally in Latin
to settlements smaller than cities, equating to "town" in English
(bearing in mind that ancient "cities" could be very small by modern
standards). The word is derived from the earlier Latin ob-pedum,
"enclosed space." Oppidum (plural oppida) is primarily used to describe a large fortified Iron Age settlement. Oppida are associated with the Celtic late La Tène culture, emerging during the 2nd and 1st centuries B.C., spread across Europe, stretching from Britain and Iberia in the west to the edge of the Hungarian plain in the east. In his Commentarii de Bello Gallico, Julius Caesar described the larger Celtic Iron Age settlements he encountered in Gaul during the Gallic Wars in 58 to 52 B.C. as oppida. Although he did not explicitly define what features qualified a settlement to be called an oppidum, they were important economic sites, places where goods were produced, stored and traded, and sometimes Roman merchants had settled and the Roman legions could obtain supplies. They were also political centers, the seat of authorities taking decisions that affected large numbers of people, such as the appointment of Vercingetorix as head of the Gallic revolt in 52 B.C. Oppida continued in use until the Romans began conquering Europe. North of
the River Danube, where the population remained independent from Rome,
oppida continued to be used into the 1st century A.D.