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.

Bern, or Berne, is the de facto capital of Switzerland, referred to as the "federal city". With a population of about 133,000, Bern is the fifth-most populous city in Switzerland, behind Zürich, Geneva, Basel and Lausanne. The Bern agglomeration, which includes 36 municipalities, had a population of 406,900 in 2014. The metropolitan area had a population of 660,000 in 2000.