Solothurn is a canton of Switzerland. It is located in the northwest of Switzerland. The capital is Solothurn.The territory of the canton comprises land acquired by the capital. For that reason the shape of the canton is irregular and includes two exclaves along the French border, separated from the rest of the canton by Basel-Land, which form separate districts of the canton. Between 1798 and 1803 the canton was part of the Helvetic Republic.
In 1803 Solothurn was one of the 19 Swiss cantons that were reconstituted by Napoleon (Mediation). Even though the population was strictly Roman Catholic, Solothurn did not join the Catholic separatist movement (Sonderbund) in 1845. Similarly, the federal constitutions of 1848 and 1874 were approved. The current constitution of the canton dates from 1987.
The canton is located in the north-west of Switzerland. To the west and south lies the canton of Bern, to the east is Aargau. To the north the canton is bounded by the canton of Basel-Landschaft. Parts of two of the districts are exclaves and are located along the French border. The lands are drained by the Aare River and its tributaries.
The landscape is mostly flat, but it includes the foothills of the Jura massif. Part of this, the massif of the Weissenstein, overlooks Solothurn and the Mitteland from the north and affords spectacular views of the Bernese Alps. The flat lands are a plain created by the Aare river. The total area of the canton is 791 km².