Solothurn (ˈsoʊlətʊərn,_ˈzoʊ- , ˈzoːlotʊrn; Soleure sɔlœʁ; Soletta soˈletta; ) is a town, a municipality, and the capital of the canton of Solothurn in Switzerland. It is located in the north-west of Switzerland on the banks of the Aare and on the foot of the Weissenstein Jura mountains.
The town is the only municipality of the district of the same name.
The town got its name from Salodurum, a Roman-era settlement. From 1530 to 1792 it was the seat of the French ambassador to Switzerland. The pedestrian-only old town was built between 1530 and 1792 and shows an impressive array of Baroque architecture, combining Italian Grandezza, French style, and Swiss ideas. The town has eighteen structures listed as heritage sites.
The official language of Solothurn is (the Swiss variety of Standard) German, but the main spoken language is the local variant of the Alemannic Swiss German dialect.
The oldest finds from Solothurn probably date from the Paleolithic era. The remains of a Mesolithic camp were discovered in 1986 during renovations of the former Kino Elite building. From the Neolithic, Bronze and Iron Age, only a few scattered items have been discovered.
The Roman settlement at Solothurn was probably built around AD 15–25 as a road station and bridge head on the road from Aventicum to Augusta Raurica or Vindonissa. A small vicus or settlement quickly developed around the castrum. Solothurn is first mentioned in 219 as vico salod[uro] on the so-called Eponastein. The name may indicate either that a Celtic settlement existed on the site before or just be a testimony to the mixed Gallo-Roman culture in the north-west provinces of the Roman Empire. It came to be known as Salodurum, this name believed to derive from a Celtic language, possibly meaning "Salo's fort," from the personal name Salo + Proto-Celtic *dūnom, meaning "fort" or "stronghold," likely influenced by the Latin durus, meaning "hard" or "strong," as in other place names. Its strategical importance lay in the position at the approach to the Rhine from southeast.