« When the Romans were seeking a crossing of the Aare over which to build their road from Aventicum to Vindonissa, they decided on a place which the Celts called Salodurum, or “Water Gate”. The settlement which the Romans founded here in around 20 AD also bore the name of Salodurum. In around 330 AD, this small town with temples and baths was converted into a castrum, or fortress, by the Roman military. »
This explains the name, Solothurn.
https://www.solothurn-city.ch/en/why-solothurn/stories-about-solothurn/history-of-solothurn
It belonged to Lorraine, then Burgundy, in 1127 to the dukes of Zähringen, in 1218 it became a free imperial city under the Holy Roman Emperor; in 1252 some nobles grew in power and around 1350 the guilds took over.
This is great: « However, in 1459 the last noble family died out and positions on the council fell to wealthy farmers, butchers and millers. »
As for Switzerland: « After the alliance with Bern in 1295, it became part of the Swiss Confederation. In 1382 the Habsburgs attacked the city, involving Solothurn in the Battle of Sempach. By the treaty of two years later, the Habsburgs renounced all claims to the territory of the city. The latter was expanded by acquisition of neighbouring lands in the 15th century, roughly up to the today's canton area.
In 1481, it obtained full membership in the Swiss Confederation. »
https://en.m.wikipedia.org/wiki/Solothurn
It belonged to Lorraine, then Burgundy, in 1127 to the dukes of Zähringen, in 1218 it became a free imperial city under the Holy Roman Emperor; in 1252 some nobles grew in power and around 1350 the guilds took over.
This is great: « However, in 1459 the last noble family died out and positions on the council fell to wealthy farmers, butchers and millers. »