In the final centuries BC, fortified towns began to appear in Celtic Europe. These are usually known by the term Caesar used for them: 'oppida'.
On the continent their defences were usually of the 'murus gallicus' type but British oppida, like Camulodunum, were often vast tracts of land loosely defended by dykes and such natural features as rivers.
Many oppida began life as settlements controlling trade routes, but a good local supply of natural resources, especially iron ore, was also important. Oppida usually developed in naturally defensible locations, such as hilltops (e.g. Bibracte), but where other factors were paramount, low-lying oppida were possible - Manching is a fine example, its prime location controlling trade outweighing considerations of indefensibility.
Oppida had many functions. They were generally the commercial, political and administrative centres of individual tribes.
At the heart of the oppida were public buildings. Some were associated with the administration of the tribal territory, like the forum at Bibracte. Others were religious, the most common ritual structure being a ditched enclosure containing a series of vertical shafts with votive offerings.
Most oppida contained mints, and numerous low denomination coins, used in trade and marketing, are found on these sites. A large range of industries and crafts were also practised in the oppida including potting, wood working, jewellery making, bronze smithing and, particularly, iron working to provide the basic tools and weapons widely required.
Craftsmen may have produced objects to sell but many probably worked for aristocratic patrons. The aristocracy generally lived in palisaded (fenced) enclosures or courtyard houses well away from the bustling main roads and gateways of the oppida. It is mainly these individuals who benefited from the imports of wine and fine tableware.
