The term oppidum (plural oppida) is Latin, originally deriving from classical sources; most significantly Julius Caesar used it to describe several locations he encountered in Gaul (modern-day France, parts of Belgium, western Germany and northern Italy) during his conquest in the mid-1st century BC. By the early 20th century oppida were argued to be a pan-European category of monument and the term has subsequently been applied to a range of sites across Europe dating from the 3rd century BC to 1st century AD.

Oppida vary significantly across Europe, encompassing well-defined, hilltop fortified sites in central France to low-lying dispersed and sprawling complexes in southern Britain. However, they do share certain characteristics: they are often enormous in size (often 100s of hectares), they frequently provide evidence as centres of trade, production and ritual, and were often involved in interacting with the expanding Roman Empire.

Translation of the latin ‘oppidum’ as ‘town’ has led to a long running debate over whether oppida can be regarded as urban. Certainly for many archaeologists they mark a radical change in the scale and organisation of societies at the end of the 1st millennium BC, before they were subsumed by Rome.

Despite their significance in Europe's past, oppida remain poorly recognised by the general public and are an underdeveloped foci for cultural and economic sustainability. Their often extremely large scale also means that they are both 'sites' and 'cultural landscapes' in themselves, making them a challenge to manage, for people to percieve, and present. Oppida thus represent a microcsom of many of the challenges we face in engaging with and presenting culural landscapes.