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 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.

In the 2nd–3rd century AD, the vicus expanded rapidly to fill almost all of what is now the old town of Solothurn, including a portion of today's suburb south of the Aare.

In addition to the normal government of the settlement, there were two mayors (magistri), and a six-member college (seviri Augustales), which was entrusted with supporting the imperial cult.

Salodurum was also home to a guard detachment of the XXII Legion, whose high command was stationed in Mainz in Germany.

There was bath house on the main street and a pottery district in the northwest of the town which have been documented archaeologically.

A cemetery with urns and cremation burials on the eastern end of the Vicus was discovered in 1762–63 during the demolition of the old church of St. Ursus.

Both the religious histories and archeological discoveries indicate that both areas remained inhabited continuously into the Early Middle Ages.

A burial memorial in the cemetery of the nearby St. Peter's Chapel dates to around the collapse of the Roman Empire.

By the middle of the 5th century, St. Eucherius of Lyon mentions the martyrdom of St. Ursus and St. Victor and a cult of saints in Solothurn.

In 1038, Emperor Conrad II held court at Solothurn and there crowned his son, Henry III King of Burgundy.

In 1252, a group of nobles that could witness and support deeds, known as consuls et cives Solodorenses, first appears in the town.

However, in 1459 the last noble family died out and positions on the council fell to wealthy farmers, butchers and millers.

In 1344 Solothurn acquired the right to appoint their own Schultheiss from the Count of Buchegg, which was confirmed by Emperor Charles IV in 1360.

In 1409, Emperor Ruprecht extended the de non Evocando privilege to include the royal High Court as well.

In 1532, the French embassy with a church and stately home was built in the eastern half of the city.

The town hall, market place and clock tower formed the political and economic centre of city life.

[10] The medieval cooperative election of the mayor and councillors led to the creation of a nearly hereditary oligarchy by the 15th century.

A number of new public buildings were also added including; the Arsenal (1610–19), the town hall with its north staircase tower (1632–34) and its eastern façade (Archive tower 1624, completed 1703–14), the Jesuit church (1680–89), the new Ambassadorenhof (1717–24), the Holy Spirit Hospital in a suburb (1735–1800) and the new classicist Church of St. Ursus (1763–90).

[10] Between 1667 and 1727, following plans by Francesco Polatta, Jacques Le Prestre Tarade and Sébastien de Vauban, the city built fortifications with eleven full and half bastions.

Following the capitulation of Solothurn on 2 March 1798, the French General Balthazar Alexis Henri Schauenburg set up a provisional government on the following day.

The eleven old Vogtei (baillywicks) were replaced by five districts: Solothurn, Biberist, Balsthal, Olten, and Dornach.

The municipal Bürgergemeinde laid claim to the assets of the defunct city-state and in 1801 it received the Sönderungsconvention, large estates and extensive forest land outside the town.

The division of property between residents and the Bürgergemeinde proved to be lengthy and could not be completed until 1978 and then only with the help of the Executive Council.

The Liberals held an average of 60% of the seats, the Social Democrats and the Conservative People's Party (CVP today), about 20% each.

[12] Solothurn is located in the north-west of Switzerland on the banks of the Aare and on the foot of the Weissenstein Jura mountains.

[17] The historical population is given in the following chart:[4] The old town was built between 1530 and 1792 and shows an architectural combination of Italian Grandezza, French style and Swiss ideas.

There are two houses and two public objects on the list; the Haller-Haus (former Bishops Palace) at Baselstrasse 61, the Sommerhaus Vigier at Untere Steingrubenstrasse 21, the Mauritius Fountain and the town clock tower.

In the tertiary sector; 1,537 or 14.1% were in wholesale or retail sales or the repair of motor vehicles, 454 or 4.2% were in the movement and storage of goods, 610 or 5.6% were in a hotel or restaurant, 583 or 5.3% were in the information industry, 975 or 8.9% were the insurance or financial industry, 1,095 or 10.0% were technical professionals or scientists, 614 or 5.6% were in education and 2,612 or 23.9% were in health care.

The education system in the Canton of Solothurn allows young children to attend two years of non-obligatory Kindergarten.