Metz is a city in northeast France located at the confluence of the Moselle and the Seille rivers. Metz is the prefecture of the Moselle department and the seat of the parliament of the Grand Est region. Located near the tripoint along the junction of France, Germany and Luxembourg, the city forms a central place of the European Greater Region and the SaarLorLux euroregion.

An oppidum is a large fortified Iron Age settlement or town. Oppida are primarily associated with the Celtic late La Tène culture, emerging during the 2nd and 1st centuries BC, spread across Europe, stretching from Britain and Iberia in the west to the edge of the Hungarian plain in the east. These settlements continued to be used until the Romans conquered Southern and Western Europe. Many subsequently became Roman-era towns and cities, whilst others were abandoned. In regions north of the rivers Danube and Rhine, such as most of Germania, where the populations remained independent from Rome, oppida continued to be used into the 1st century AD.